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25

Anatomy

Oral Cavity and salivary glands

Saleh Bani-Hani

Safwan Abualrub

Monday, 24/10/2011

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Subject: Anatomy Lecture 1

Done By : Safwan Abualrub

Date: 24-10-2011

Oral Cavity and salivary glands

As we know the digestive system consists of G.I tract and associated

organs. The G.I tract extends from the oral cavity to the anal canal and it

consists of oral cavity, pharynx, esophagus , stomach, small intestine and

large intestine. The associated organs include teeth, tongue, salivary glands,

liver, gallbladder and pancreas.

Now let’s start with the oral cavity structure

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Oral Cavity

The oral cavity is divided into two parts, the outer part is the vestibule

which lies outside the teeth between the teeth and the lips, and the inner

part is the mouth cavity proper. The tongue is found in the mouth cavity

proper and here if we looked at the lower surface of the tongue (figure 11-

72 B), we can see a fold of mucous membrane that lies in the midline of the

tongue which is called the lingual frenulum. On each side of this lingual

frenulum we have 3 structures: most lateral is lingual vein and most medial is

the lingual artery and in between we have lingual nerve. The clinical

significance of the mucous membrane of the inferior surface of the tongue

is that it is thin which allows rapid absorption of sublingual drugs through

the lingual vein. A good example is Nitroglycerine which is administered via

sublingual route to relieve angina pain in emergency situations.

If we look at the base of the frenulum we can see that there are two

papillae, at these papillae we have 2 or 3 openings which represent opening

of submandibular duct (figure 11-72 B). Just lateral to the papillae , we have

small elevation of mucous membrane beneath the tongue, and because this

membrane or fold lies beneath the tongue then it is called sublingual fold.

The sublingual fold as we can see in the figure is made by the sublingual

gland itself, and contains the openings of the ducts of this gland. So if we

remove this fold we will find the sublingual gland.

Finally we have to state the location of the opening of the parotid gland

duct which lies in the vestibule opposite to the second upper molar tooth.

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Anterior two thirds components

General Tongue Structure

When we talk about the tongue, bbbbbbbbbbbbbbbbbbbbbbbbbbbn we have

to divide it into 2 parts, anterior two thirds also called palatine tongue, and

posterior one third also called pharyngeal tongue which are separated by the

sulcus terminalis or terminal groove ( figure 11-72 A). The anterior two

thirds and posterior one third are different in location, in structure, in

nerve supply and even in embryonic origin. For example the anterior two

thirds originate from the 1st pharyngeal arch while the posterior one third is

derived from 2nd and 3rd pharyngeal arches.

The anterior two thirds contain mucous membrane and muscles. The mucous

membrane contains large number of papillae which contain taste buds. It also

contains mucous and serous glands. Note that the mucous membrane of the

tongue whether we are talking about anterior or posterior part of the

tongue, it is made from stratified squamous epithelium. Esophagus lining is

also made from stratified squamous epithelium.

Now let’s have a look on the papillae (figure 11-73).

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1- Vallate papillae (Circumvallate papillae)

In total, there are 10 vallate papillae, 5 or 6 vallate papillae on each

side of the tongue (in the book 7-12)just anterior to the sulcus

terminalis, mostly found in the anterior two thirds of the tongue

(figure 11-73). Each of these vallate papillae contains about 500 taste

buds which are responsible for taste sensation. This means that the

vallate papillae contain about 5000 taste buds as total ( 10 X 500 ).

The total number of taste buds in the full tongue is 10000; this means

that the vallate papillae contain half of the taste buds in the tongue.

Now each of this large papilla is surrounded by a deep cleft and a fold

of mucous membrane. Close to this cleft or space we have serous

glands called Von Ebner glands (figure 11-74). These glands secrete

watery serous secretions to dissolve the food and thus stimulate the

buds that are located at the sides of the papillae.

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2- Filliform papillae

If you looked at your tongue, you will see some white dots on the

dorsal surface of the anterior two thirds of the tongue, these are

filliform papillae which are the smallest papillae and the most

numerous ones. The filliform papilla is conical in shape and has

keratin; this keratin gives the whitish colour that we see in our

tongue. These papillae don’t contain taste receptors, they only contain

touch receptors(mechanical receptors)..

3- Fungiform papillae

These papillae are located between filliform papillae, which are red in

colour and are mushroom shaped. They are concentrated near the

sides and at the tip of the tongue and contain some taste receptors.

4- Foliate papillae

They are poorly developed in humans. They are found in well developed

state in animals and contain some taste buds.

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Posterior one third component

Histology of taste bud in general:

Taste receptor cell which is responsible for taste function.

Nerve fibers which emerge from the facial nerve in the anterior two

thirds.

Supporting cells (found at the rim of this structure).

Basal cells which generate taste cells and the supporting cells.

Now if we look at the posterior one third. It is made from mucous

membrane and lymph tissue.

The lymph tissue of the tongue is called lingual tonsil. It is part

of our lymphatic system.

** Remember that we have the palatine tonsils, pharyngeal tonsils and

lingual tonsils.

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Muscles of the tongue

Palatine tonsils are located at the beginning of the oropharynx on each

side. The pharyngeal tonsils are located under the mucous membrane

of the pharynx on its roof. Lingual tonsils are found on the posterior

one third of the tongue.

The mucous membrane of the posterior part has very small

number of taste buds while the majority of the buds are found

in the anterior two thirds. We also have small number of taste

buds in the epiglottis of the larynx and in the soft palate.

- Notes from the 3rd lecture for more clarification:

1- Do we have papillae in the posterior compartment

- Anatomically there are papillae in the anterior two thirds, epiglottis

and soft palate , but in the posterior one third we have no papillae

(anatomically).

But from functional view, we can say that the vallate papillae are part

of the posterior one third because these vallate papillae are not

supplied by the facial nerve which gives sensory supply to the anterior

two thirds, instead they are supplied by the glossopharyngeal nerve

which supplies the posterior one third of the tongue.

So anatomically vallate papillae are found in the anterior two thirds

anterior to the sulcus terminalis but functionally they are part of the

posterior one third.

When we talk about the muscles of the anterior two thirds, we talk about

intrinsic muscles and extrinsic ones.

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1- Intrinsic muscles

Intrinsic muscles of the tongue are muscles that originate and insert

inside the tongue; they are only found inside the tongue. The fibers

of intrinsic muscles are organized into 3 types of fibers: longitudinal

(superior and inferior longitudinal fibers), transverse or horizontal

and vertical fibers. The function of these muscles is to change the

shape of the tongue.

2- Extrinsic muscles

Extrinsic muscles originate outside the tongue but insert inside it.

The genioglossus muscle is the most important, it originates from the genial

spine of the mandible to the lateral sides and the dorsum of the tongue as

illustrated in the transverse section in figure below.

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The importance of the muscle arises from the fact that it is the only muscle

that can protrude the tongue (move it anteriorly). All the other 3 muscles

can retract the tongue but can’t protrude it.

** Note: The doctor read the origin, insertion and action of each muscle as

in table 11-8.

In the oral cavity there are some folds (refer to figure 11-72 A and the

figure below). The first one is called palatoglossal fold that extends from

the palate to the tongue and is made up by the palatoglossus muscle. The

second one is called that palatopharyngeal fold which extends from the

palate to the pharynx and is made by a muscle called the palatopharyngeus

muscle. Between these two folds we have the palatine tonsils which are

located in tonsilar beds. (fig 11-72 A). The lateral wall of the tonsilar bed is

made from superior constrictor muscle of the pharynx. (These relations are

clear in the following figure)

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pg = palatoglossal fold, pp=palatopharyngeal fold, SC=superior constrictor muscle

Note from 3rd lecture :

Are there muscles in the posterior one third ?

- For the extrinsic muscles palatoglossus and styloglossus muscles

attach on the posterior one third.

- for the intrinsic muscles, the vertical muscles are only found in the

anterior 2/3 , the transverse muscles position is not really clear,

the superior longitudinal muscles are found in both the anterior

and posterior thirds of the tongue but more in the anterior 2/3.

The doctor said nothing about the inferior longitudinal muscles.

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Nerve & Blood Supply of the tongue

Nerve supply:

Motor supply

All of the intrinsic and extrinsic muscles of the tongue are supplied by

the hypoglossal nerve (cranial nerve XII) except the palatoglossus

muscle which is supplied by the vagus nerve( cranial nerve X)

All of the intrinsic muscles of the larynx without exceptions are

supplied by vagus nerve.

All of the muscles of the pharynx are supplied by vagus nerve except

the stylopharyngeus muscle which is supplied by the glossopharyngeal

nerve (cranial nerve IX).

All of the muscles of the palate are supplied by the vagus nerve

except the tensor veli palatini muscle which is supplied by the

trigeminal nerve (cranial nervel V )

Sensory supply

From anterior two thirds of the tongue :

a- General sensation: from lingual nerve which is a branch of

trigeminal nerve

b- Taste sensation: from facial nerve (cranial nerve VII) for all

papillae except vallate which are supplied by glossopharyngeal

nerve.

From posterior one third of the tongue:

Both general sensation and taste sensation by the same nerve which is

the glossopharyngeal nerve. Note that glossopharyngeal supply all

parts of the posterior oral cavity. For example: tonsils, oropharynx ,

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Teeth Anatomy

Eustachian tube, and posterior one third of the tongue are supplied by

this nerve).

Blood supply:

1-Main one is lingual artery.

2- Tonsilar branch of facial artery.

3- Ascending pharyngeal artery which is a branch of the external carotid

artery.

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We have primary teeth (deciduous teeth) and secondary teeth (permanent

teeth). The primary teeth are 20 in number (10 in each jaw) while the

secondary teeth are 32 in number (16 in each jaw).

From the anatomical view, if we looked at the secondary teeth from the

central line we start with the 1st incisor(central incisor) then the 2nd

incisor(lateral incisor) , then the canine , then 1st premolar , then 2nd

premolar , then 1st molar, then 2nd molar, and lastly 3rd molar(wisdom tooth).

Now when we come to the primary or milky or deciduous teeth from the

central line we have the central incisor then the lateral incisor , then the

canine, then the first molar and then the second molar.

So what are the teeth that are missing from the primary group ?

Answer: the two premolar and the 3rd molar.

Now concerning the timing of eruption:

The eruption in the primary teeth start with the central incisor at

about 6-8 months of age, then the lateral incisor, then 1st molar, then

canine and the last one is the 2nd molar. In general the lower teeth

erupt before the upper ones.

The eruption in secondary teeth does not start with the central

incisor; it starts with the 1st molar, then central incisor, then lateral

incisor, then 1st and 2nd premolars, then the canine, then 2nd and 3rd

molars.

*Note the 3rd molar is called wisdom tooth and it erupts in all adults. It

erupts between 17 and 30 year old, but some people feel it while others

don’t. This can be explained by the direction of growth of the wisdom tooth,

if it grows straight then no pain can be felt, but if grows obliquely then pain

is felt.

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** The doctor said that we have to remember the names and age of eruption

of each tooth especially on which comes first, which comes last in each

group.

*** I was not provided by the slides so I did my best to get similar pictures

that contain the described info.

****The doctor repeated the same info again and again so I put the

information in a more summarized way.

Special thanks to my friends: Tariq kewan, Mohamad Widyan,, Ahmad Kofahi,

Alaa Hmaidat ,Ibrahim Manasrah, Ghassan Shbool, Mohammad Jibril,

Mohammad Refai, Omar Bataieneh.

“It is amazing how a person can make your life very special”

The END

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Anatomy

Teeth, Salivary Glands, Palate, Pharynx

Saleh Bani-Hani

Oday Manaseer

Monday, 24/10/2011

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BismAllah, this is the second anatomy lecture of the GI system, the doctor will continue talking about

the teeth, then he will cover up the salivary glands, the palate and the pharynx, good luck =)

The Teeth

It’s divided into two parts, the external part which we can see is the crown, and the

internal part embedded within the alveolar fossa; the root.

The crown and the root are composed of many

layers:

1. The outer layer : Enamel in the crown.

Cementum in the root.

2. The middle layer: Dentin.

3. The inner layer: Pulp.

The blood supply and innervations of the tooth

are found in the Root Canal; begins in the root

opening and terminates in the pulp.

The root is connected to the jaw bone by a ligament called Periodontal Ligament,

functioning in fixation of the tooth within the bone.

Salivary Glands:

There are three large salivary glands on each side of the

oral cavity, the largest is the Parotid, the second

largest is the Submandibular, and the third one is

called Sublingual.

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In addition to those three large salivary glands, we have many individual salivary cells

distributed throughout the oral cavity.

The Parotid Gland:

It’s triangular in shape, the apex downward and the

base upward. In order to study the structure and

the relationships of the gland we have to make

transverse section, and we’ll talk about the

structures that are located laterally or superficially to the gland, or the other deep ones.

The parotid duct runs anteriorly (or superficially) to the masseter muscle, after it

passes the anterior border of the masseter muscle it turns medially, penetrate the

buccinators muscle, finally it opens to vestibules very close to the second upper molar

tooth. Now the doctor is illustrating how you can feel the duct! Just put your hand

under you upper jaw after closing it against the lower one, it’s there somewhere in that

area, almost one finger below the zygomatic bone.

Now we will talk about the

relations of the parotid

gland:

The gland is surrounded by

a fibrous capsule originated

from the investing deep

cervical fascia.

Superficial to the gland; we

have skin and we have a

nerve; it’s a branch of the

cervical plexus; it’s called

the great auricular nerve.

Deep to the gland; there is

the Superior Constrictor

Muscle (which form the

lateral tonsilar bed)

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The ramus of the mandible lies anteriorly to

the gland, and the muscles related to the

ramus is also lies anteriorly, those muscles are

the masseter which lies superficially to the

ramus, and the medial pterygoid muscle lies

deeply.

The structures located posteriorly to the

parotid gland include (from superficial to

deep) the mastoid process, the styloid

process and the carotid sheath, and anything

related to these structures is included as well:

Structures related to mastoid process are sternocleidomastoid muscle and the posterior

belly of digastrics (it’s a small muscle located behind the jaw), there’s also a small artery

called the posterior auricular artery.

Muscles originating from the styloid process include: the styloglossus, the stylohyoid

and stylopharynx.

There are very important structures within the carotid sheath include the internal

carotid artery, internal jugular vein and the last four cranial nerves (9, 10, 11, 12).

Processes of the parotid gland:

The parotid gland extend to the most posterior part of the mandibular fossa and it’s

called the The glenoid process. The head of the mandible when it articulates with the

fossa it leaves a little space in the fossa, and that’s where the parotid gland extends

posteriorly.

The second process extends anteriorly, superficially to the masseter muscle. Sometimes

it’s separated from the parotid gland and called the Accessory Parotid Gland.

The third process or extension between the ramus of mandible and the medial

pterygoid muscle called the Pterygoid Process.

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A very important structure passes and penetrates the parotid gland, it’s the facial nerve:

The facial nerve passes out from the skull through the stylomastoid foramen. It

divides the parotid gland into superficial part and deep part. Within the deep part

the external carotid artery gives its two terminal branches; the one ascending

upward called Superficial Temporal, and one runs deep it’s called Maxillary. Also in

the deep part the superficial temporal vein and the maxillary vein join each other in

the deep part of the parotid gland to form the retromandibular vein which descends

behind the mandible.

Submandibular Gland:

It’s located within the submandibular fossa, it’s divided into large superficial part

located laterally to the mylohyoid muscle and deep part; the deep part turns

medially to the mylohyoid muscle.

The duct of the submandibular gland opens through two or three openings at the

small papilla at the base of the lingual frenulum.

The relations of Submandibular gland:

Anteriorly there’s the anterior belly of the digastric muscle.

Posteriorly there’s the posterior belly the digastric muscle. The stylohyoid muscle,

the stylomandibular ligament and part of the parotid gland are also found

posteriorly.

Medially we have the mylohyoid

Laterally lies the body of the mandible, inferiolaterally we have other structures like

skin and a very thin muscle like a sheet of paper called the Platysma, also we have

investing of the deep cervical fascia, lymph nodes, the cervical branch of the facial

nerve.

The Facial Nerve:

It comes out from the stylomastoid foramen, passes through the parotid gland and divides it

into two parts; deep and superficial parts. Then it comes out from the anterior border of the

gland, at this point it gives off five branches, they are all motor branches, they supply facial

expression muscles. These branches are; temporal, zygomatic, buccal, mandibular and cervical.

So the cervical branch of the facial nerve crosses the submandibular gland.

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Sublingual Gland:

It’s drained by 8-20 excretory ducts, all of which open to the sublingual pilca (or so

called plica fimbriata)

plica fimbriata: is a slight fold of the mucous membrane on the underside of the tongue which runs laterally on either

side of the lingual frenulum…wiki

Histology of salivary glands:

It’s composed of a round structure called acini. There are two types of acini

in the salivary glands; we have

serous acinus and mucous acinus.

Comparison between the

serous and mucous:

The serous: the nucleus is round

and centrally located, the cells contain

a lot of rough endoplasmic reticulum and

produce enzymes such as amylase

enzyme, so it absorbs high amount of stain

and the cells appear darker under microscope.

The mucous: the nucleus is flat and located basally, because the

mucous doesn’t absorb high amount of stain, so it looks pale under the

microscope.

The parotid gland is a serous gland, the sublingual is mucous gland, but the submandibular

is mixed gland, produce mucous and serous.

serous

mucous

Serous

demilunes

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There’s a characteristic feature in the mixed glands; which is that the serous

acini cells cover or overlie part of the mucous acini, this feature is called

serous demilunes.

The saliva, after it was secreted by the cells, it passes through what is called

intercellular canaliculi, these canaliculi join each other to form intercalated

duct, in turn these intercalated ducts join together and form a wider duct

called the striated duct; it’s called striated because it has many folds of

mucous membrane to increase the surface area for ion transporting

between the saliva and the blood; for example the potassium and

bicarbonate move from the blood to the saliva, while the sodium and

chloride goes through the opposite direction, so comparing to the blood

the saliva shall contain less sodium and chloride but higher concentration

of potassium and bicarbonate. And these folds under the microscope give

striated appearance to the duct.

The wall of the intercalated duct is formed of simple cuboidal epithelium, with round and

centrally located nuclei, while the wall of the striated duct is made of simple columnar

epithelium.

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The Palate:

It’s divided into two parts; the Hard palate and Soft palate.

The hard palate is composed

of mucous membrane and

bones, but the soft palate is

composed of mucous

membrane and muscles,

there are five muscles within

the soft palate as we will see

later.

Bones of hard palate:

The anterior 2/3 is formed by the palatine

plane of maxilla, and the posterior 1/3 is

formed by horizontal plane of palatine

bone.

Anteriorly in the midline of the hard palate

lies the incisive foramen, where the

nasopalatine nerve passes and supply the

anterior part of the mucous membrane, it’s

a branch from the maxillary and gives

sensation to that area.

In the posterior part we have two

foraminae, greater and lesser palatine

foraminae. From the greater palatine passes the greater palatine nerve; a

branch of maxillary nerve and supplies the posterior surface of the mucous

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membrane. The lesser palatine nerve, another branch of the maxillary

nerve, passes through the lesser palatine foramen which goes backward to

supply the soft palate. The soft palate is also supplied by the

glossopharangyeal nerve.

In general, the sensory innervations of the palate are branched from the maxillary nerve

through the nasopalatine, greater palatine and lesser palatine branches, except the most

posterior part of the soft palate is supplied by the glossopharyngeal nerve.

Concerning the motor supply, there are five muscles in the soft palate, all

are innervated by the vagus nerve.

Muscles of the soft palate:

There are two folds in the soft palate area, one anterior to the tonsil and

the other is posterior; the anterior one is made by palatoglossal muscle, the

posterior fold is made by the palatopharyngeal muscle. Between these two

fold lies the tonsilar fossa.

In the center of the soft palate we have a sort of fibrous membrane, the

Palatine Aponeurosis, it either receives insertions or gives origins. It gives

origin to the palatoglossus, palatopharyngeus and the muscle that forms

the internal section of Uvula.

The Vagus nerve:

It supplies all the muscles of the larynx.

All the muscles of the pharynx except stylopharyngeal muscle.

All muscles of the palate except tensor vili palatini which is supplied by the trigeminal nerve

(through the mandibular nerve).

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Two muscles come from superior and are inserted to the soft palate;

levator veli palatine (elevates the soft palate when swallowing) and tensor

veli palatine (makes the palate tense).

All of these muscles are innervated by the vagus nerve, except the tensor veli palatine which

is supplied by trigeminal nerve

The Pharynx:

It is divide into three parts,

behind the nose it’s called

Nasopharynx, when located

behind the oral cavity it’s called

Oropharynx, and when located

behind the larynx it’s called

Laryngeopharynx.

It extends from the base of the

skull to the lower border of the

cricoids cartilage of the larynx

where the esophagus starts at the

level of C6 vertebra.

The pharynx has no anterior wall;

it has posterior and lateral walls

but not anterior wall.

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Pharyngeal Muscles:

In general these muscles are arranged in two patterns;

inner longitudinal, and outer circular (called

constrictor). This arrangement is the exact opposite of

what is found in the remaining of the GIT.

When the longitudinal muscles contract they elevate

the pharynx, while the outer constrictor muscles when

contract push the food downward.

The constrictor muscles:

1. Superior constrictor muscle, it forms the lateral wall of the tonsilar

bed, and it reach deep to the parotid gland. It originates from

pretygoid process of sphenoid and the mylohyoid line in the

mandible, inserted in the base of the skull and into median raphe.

Median raphe: a midline structure of a fibrous connective tissue and it receives

all the muscles related to the pharynx.

2. Middle constrictor muscle, originates from the hyoid bone and

stylohyoid ligament.

3. Inferior constrictor muscle arises from the cricoids and thyroid

cartilages and inserted in the median raphe.

The most inferior fibers of the inferior constrictor form the superior

esophageal sphincter

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We have two sphincters at the openings of the esophagus;

superior esophageal and inferior epigastric. But these

sphincters are not considered as real anatomical sphincters,

only considered as physiological sphincters. That means at

these areas the muscles don’t become thicker to make the

sphincter, but functionally act as sphincter because they have

hypertonia. When a person dies those sphincters disappear,

because again they are not real sphincters.

The muscles of the pharynx are skeletal muscles, although they act involuntary. The

first phase of swallowing process in the oral cavity is voluntary, and just when the

food touches the pharynx will stimulate a reflex contraction of the pharyngeal

muscle.

The nerve supply to pharyngeal muscles:

The vagus nerve gives the motor supply to all of the pharyngeal

muscles except the stylopharyngeus muscle; which is supplied by the

glossopharyngeal nerve.

The sensory supplement depends on the area, the mucous

membrane in the nasopharynx is supplied by the maxillary nerve,

mucous membrane of oropharynx is supplied by the

glossopharyngeal nerve, and the mucous membrane in the area of

laryngeopharynx is supplied by vagus nerve.

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If we remove the posterior wall of the pharynx we

see the nose, oral cavity and the larynx.

Blood Supply:

The palate is supplied by ascending pharyngeal, facial and maxillary

artery, all of which are branches from the external carotid artery.

The pharynx is supplied also by the ascending pharyngeal, facial and

lingual artery (also a branch of the external carotid artery).

La Fin

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Medical Mystery, 1880s

Josephene Myrtle Corbin, the Four-Legged Woman, was born in Lincoln County, Tennessee in 1868. Rather than having a parasitic twin, Myrtle’s extra legs resulted from an even rarer form of conjoined twinning known as dipygus, which gave her two complete bodies from the waist down. She had two small pelves side-by-side, and each of her smaller inner legs was paired with one of her outer legs. She could move the smaller legs but was unable to use them for walking. At the age of 19, she married a doctor named Clinton Bicknell and had four daughters and a son. It has been said that three of her children were born from one set of organs, two from the other. Myrtle died on May 6, 1928.

“EVERY DAY THE SUN RISES IT CALLS UPON US, “OH

PEOPLE! I AM A NEW DAY; I AM AN OBSERVER OF YOUR

ACTIONS. TAKE ADVANTAGE OF ME FOR I WILL NOT

RETURN UNTIL THE DAY OF JUDGMENT.” “OH, SON OF ADAM YOU ARE NOTHING BUT A FEW

BREATHS. ONCE ONE BREATH GOES OUT, PART OF YOU GOES WITH IT. IN THE SAME WAY

THAT PART OF YOU HAS GONE, SOON ALL OF YOU WILL GO.” -AL-HASAN AL-BASRI

Oday Manaseer

0

Anatomy

Esophagus and Abdominal Wall

Saleh Bani-Hani

Helda Wasfi

Tuesday, 25/10/2011

30

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1

الرحيم الرحمن هللا بسم

Dear colleges, we really did our best to organize this lecture as possible as we can coz it was full of crosswords . The first 9 pages are repetition of the last two lectures plus few more information. Please refer to the slides while you are reading and forgive us if there are mistakes .

In the beginning, we will review the last two lectures and we will answer

some of the questions which were asked by some students, and also we will list

some information which we forgot to mention in the last two lectures.

Concerning the tongue, one of the students asked me between the

two lectures about whether the posterior third of the tongue has muscles or not,

concerning the:

1- Extrinsic muscles of the tongue: it is very clear that for example the

styloglossus and the palatoglossus are inserted in the tongue including its

posterior one third, so there are muscles in the posterior one third.

2- But when we come to the intrinsic muscles, the situation is not clear, I (Dr)

looked into three books to find a clear answer for this.

(If you remember concerning the intrinsic muscles of the tongue, we know that

there are superior longitudinal, inferior longitudinal, transverse, and vertical

fibers.)

** Concerning the vertical fibers these are present only in the anterior 2/3

of the tongue. In fact, they are present in the most anterior part of the tongue.

** The transverse fibers it is not clear whether they are present in the

anterior 2/3 only or in all parts of the tongue, coz in one book they mention that

the transverse fibers arise from fibrous tissue located in the midline called

median fibrous septum (we forget to mention this in the last lectures), in fact

this septum gives the origin not only of the transverse but also other intrinsic

muscles.

2

** The longitudinal fibers In one book, it is clear that at least the sup.long.

muscle is present not only in the ant. 2/3 but also in the pos. 1/3, coz in that

book the author mentioned that the sup.long fibers reach very close to the

epiglottis, and as you know this indicates that these fibers reach the pharynx; I

think they mean the pharyngeal part of the tonsil which is the posterior 1/3.

Now very important point concerning the papillae , we mentioned

that there are no papillae in the posterior 1/3, this is true, but here we have

confusing points concerning the circumvallate (vallate) papillae which are very

important. In the last lecture, we mentioned that there are about 10 vallate

papillae containing about 50% of the taste fibers. If you remember anatomically,

these vallate papillae are located as part of the ant.2/3 coz they are located ant.

to the sulcus terminalis (terminal groove) , but they are supplied by the

glossopharyngeal nerve not by the facial nerve. I think it is good to remind you

about the nerve supply to the tongue at least concerning the taste; we

mentioned that the taste fibers that arise in the ant.2/3 are part of the facial

nerve, while the taste fibers that carry the taste from the pos.1/3 of the tongue

are part of the glossopharyngeal nerve. Now we know that the taste fibers that

carry the taste from these vallate papillae are branches of the glossopharyngeal;

that is why they consider these papillae as part of the pos. 1/3. Again, vallate

papillae anatomically are located in the ant.2/3 because they are located ant. to

the sulcus terminalis which marks the border between the ant.2/3 and the

pot.1/3, but functionally they are supplied by the same nerve which carries the

sensation from the pos.1/3 of the tongue which is the glossopharyngeal nerve,

so in most books they consider these vallate papillae as part of the post.1/3 of

the tongue. I hope it is clear now .

When we look at this figure, it is very important to see the tonsils, the

tonsillar beds and the boundaries of the tonsillar fossa opening. This is the tonsil

now ant. to the tonsil here we have the palatoglossal fold made by the

palatoglossus muscle, post. to the tonsil we have the palatopharyngeal muscle

which forms the palatopharyngeal fold , and the lateral wall of the bed is

formed by the superior constrictor muscle which is the most superior muscle of

the pharynx .

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Now when we come to the nerve supply of the tongue; the taste sensation:

1- The ant.2/3 EXCEPT the vallate papillae facial nerve.

2- The post.1/3 PLUS the vallate papillae glossopharyngeal nerve.

Now concerning the general sensation such as pain, temperature, and touch:

1- Ant.2/3 supplied by the lingual branch of the trigeminal nerve.

2- Post.1/3 supplied by the glossopharyngeal.

So again when we open our mouth and look to the most posterior part,

remember the glossopharyngeal nerve (it supplies the oropharynx, the tonsils,

the post.1/3 for both general sensation and taste sensation of the tongue).

This figure shows the sites of the openings of the ducts of the different

salivary glands.

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1- Parotid duct opens within the vestibule close to the second upper molar

tooth.

2- Submandibular each of the two submandibular glands opens into 2 or 3

openings just lateral to the base of lingual frenulum (it is a fold of mucous

membrane at the midline of the inferior surface of the tongue).

3- Lateral to these papillae (I think he meant the openings of the two

submandibular glands) there is a fold, and coz it is located underneath the

tongue it is called sublingual fold which receives the numerous openings

of the sublingual gland. The gland is located underneath this fold; I mean if we

remove this mucous membrane, we will find the sublingual gland.

((The doctor here advised us to attend the lectures and then study them from the book, but he emphasized that he'll concentrate on the important things in his lectures))

PAROTID gland: I think we covered this gland in the last lecture, but

I forgot to mention some points. We will go back to the structures which pass or

are located within the gland.

We mentioned that the facial nerve after it passes through the stylomastoid

foramen, it will enter this gland and divide it into superficial part and deep part.

In the deep part, we have arteries and veins; the external carotid artery will

divide into two terminal branches which are: superficial temporal artery and

maxillary artery, also the superficial temporal vein and the maxillary vein join

each other within the deep part to form what we call retromandibular vein (we

call it retro- coz it descends behind the mandible). Also there are large numbers

of lymph nodes; we call them parotid lymph nodes. Now deep to this gland, we

have a nerve which supplies or carries the parasympathetic fibers for this gland

and in fact this presents the most nerve supply for this gland (that’s what the dr

said O.o); this is called auriculotemporal nerve, this nerve represents the post-

ganglionic parasympathetic fibers.

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** We have the glossopharyngeal nerve (which supplies the parotid in general)

contains the pre-ganglionic parasympathetic fibers which terminate within what

we call the otic-ganglion which is located in the infra-temporal fossa just below

the foramen ovale. So, the otic-ganglion receives the pre-ganglionic

parasympathetic fibers of the glossopharyngeal nerve then the nerve sends

within this otic-gangion the post-ganglionic parasympathetic fibers that form

what we call the auriculotemporal nerve which supplies the parotid gland.

So again this nerve (auriculotemporal nerve) consists of the post-ganglionic

parasympathetic fibers that arise from the otic-ganglion and supply the parotid

gland.

** You should remember the relationship; the anterior, the posterior, superficial

and deep. The deep layer is made by the superior constrictor muscle; this muscle

is anatomically related not only to the parotid gland but also to the tonsils (it

forms the lateral wall of the tonsilar fossa).

Submandibular gland:

** It's important to remember the structures which are anatomically related to

the submandibular gland at least the superficial part.

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6ab3an the submandibular gland is located within the submandibular fossa.

So when we come to the superficial part:

Anteriorly:

We have the anterior belly of digastric muscle.

Posteriorly:

We have the posterior belly of digastric muscle, stylohyoid muscle and

stylomandibular ligament.

Medially:

We have mylohyoid muscle and its nerve (mylohyoid nerve) and blood vessels.

Also, we have hyoglossus muscle, lingual nerve, and hypoglossal nerve.

Superficially:

We have skin, platysma, deep fascia or the investing layer of deep fascia of the

neck (deep cervical fascia) and then we have lymph nodes, also the cervical

branch of the facial nerve, also we have facial vein which is located superficial to

this duct.

Do you remember the 5 branches of the facial

nerve? -Put your hand on your cheek, your

fingers tend medially, the thumb up and the

little finger down-

1- Temporal - thumb

2- Zygomatic - index-

3- Buccal - middle finger

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4- Mandibular - ring

5- Cervical - little finger

Histology of the major 3 salivary glands:

1- Parotid gland: is a serous gland (formed of serous acini) and we said that the

serous is characterized by the centrally located round nuclei.

2- Sublingual gland: are mainly mucus and the mucus acini their nuclei are flat

and basally located.

3- The submandibular: is mixed mucus and serous. In this gland, we might have

serous demilunes (we mean by this that we have mucus acinar partially

surrounded by serous cells).

These serous cells that surround the mucous

acinus are called serous demilunes which are

expected to be found in the submandibular

gland.

Nerve supply to the salivary glands:

1- The parotid gland is supplied by glossopharyngeal.

2- The facial nerve carries the parasympathetic fibers to the other 2 glands

(sublingual and submandibular).

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Pharynx:

We divide the pharynx into nasopharynx,

oropharynx, and laryngiopharynx.

Remember that the pharynx has no

anterior wall because forward it opens to

the nasal cavity, oral cavity & the larynx respectively. Its wall consists of mucosa,

sub mucosa, muscles & adventitia (connective tissue).

The muscles are skeletal but they can act both voluntary & involuntary; we

can use them voluntary but also when we swallow food & when the food touch

the mucus membrane of the pharynx this leads to reflex contraction to these

muscles -skeletal muscles- {you heard about reflexes: it means involuntary;

when you stop providing appropriate stimulus to certain part of our body, this

leads to involuntary motor response}.

Pharyngeal tonsils are located in the roof of the pharynx. So by now we have

3 tonsils: palatine, lingual, and pharyngeal which is located at the roof of the

pharynx.

Now in the lateral wall of the

pharynx in the nasopharynx, we see

the openings of the auditory

(Eustachian tube). There is a very

important clinical point related to

this structure: in case of infection to

the upper respiratory tract this leads

to congestion and this congestion

will lead to obstruction of this opening. In this case, it is not good to fly in the

airplane; because if the airplane starts to descend, this will lead to a sudden

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increase in the air pressure. If the Eustachian tube is closed, this will create

negative pressure within the middle ear and when the air pressure increases

suddenly this will create pressure on the external surface of the drum and this

may lead to perforation of the drum. So in this case, you can swallow something

because when we swallow anything this will lead to the opening of the

Eustachian tube. So people in this case are advised to chew gum because there

will be continuous swallowing of the saliva and the Eustachian tube will be

opened otherwise the result will be painful and may lead to perforation of the

drum.

Because as you know the middle ear contains very small amount of air, in case of

obstruction this air will be absorbed in the middle ear and this will create a

negative pressure in the middle ear so when someone descends rapidly as in the

plane inside there is –ve pressure, outside atmospheric pressure increase this

will create high pressure on the external surface of the drum, this leads to a very

painful situation and may lead to perforation of the drum.

Another clinical point concerning the tongue; when we described the action of the extrinsic muscle of the tongue, we mentioned that the only muscle that protrudes the tongue is

Genioglossus which arises from the mental

spine (located inside the mandible). Now the right Genioglossus will pull the tongue forward and push it to the left {Dr. said it acts by pushing not pulling}, the left one will do the same thing but it will push the tongue to the right. So when we use them together, the tongue will be protruded in the midline (this is the normal situation). Now if there is lesion in the hypoglossal nerve (which supplies almost all muscles of the tongue except palatoglossus), so in case of damage of the right hypoglossal nerve, the tongue will be deviated to the right (if you ask the patient to protrude his tongue and his tongue is not in the midline; it is deviated to the right, this means that the lesion is in the right hypoglossal nerve and the left hypoglossal nerve is working) and vice versa; coz as we said each Genioglossus muscle pushes the tongue to the other side NOT to its side.

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So in case of lesion or damage of one hypoglossal nerve, we can know that by asking the patient to protrude his tongue; the tongue will be deviated to the site of the lesion:

If it is deviated to the right the lesion is in the right nerve

If it is deviated to the left the lesion is in the left nerve

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Now the doctor puts a slide about swallowing and he said he just wanted

to remind us about the functions of the tongue and palate coz we took the process of swallowing in physiology lectures :

* Functions of the tongue:

1- Contribute to the swallowing

2- Taste

3- Mixing of the food

4- Speaking (language)

* Functions of the palate:

1- Contribute to the process of swallowing

2- Contribute to the language O.o.

Now concerning the anatomical activity; when we swallow something, the palate will be elevated. Normally, the pharynx is opened. In the process of swallowing, the soft palate will be elevated; it will reach the posterior wall of the pharynx and this elevation is done by levator velli palatini, so the food can't go to the nasopharynx. Also, the tongue will be elevated and touch the soft palate by palatoglossus & styloglossus muscles. Also, the larynx & pharynx will be elevated & the epiglottis will go backward and this will lead to the closure of larynx, so the food or bolus will find only one way opened which is the lower part of the pharynx.

Bolus: a ball-shaped mass moving through the digestive tract [wiki]

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Finally we will begin a new subject

Now we come to the esophagus:

The esophagus extends as a continuation of the pharynx at the lower border of the cricoid cartilage which is part of the larynx, so the laryngiopharynx is located behind the larynx. At the lower border of the cricoid cartilage, the esophagus starts. In the neck, it will descend behind the trachea, and in the chest it will descend first in the superior mediastinum then in the posterior mediastinum; simply it will descend in front of the vertebral column, so the esophagus will be among the most posterior structures in front of the cervical & thoracic vertebrae until it reaches about the level of T10 vertebra; here it will pass through what we call esophageal hiatus of the diaphragm slightly to the left of the midline. After this, it will enter the abdomen, within the abdomen it descends about 0.5 inch (1.5 cm). The esophagus consists of 4 layers: mucosa, sub mucosa, muscles, and adventitia (CT). [The outer layer of the organs of the abdominal cavity we call it serosa which is the visceral layer of peritoneum, but we don't have peritoneum here -pointing to the thorax- so we call the outer layer adventitia].

Now when we come to the epithelium, what do you think is the type of the

epithelium of the esophagus? Two types (same 2 types of the pharynx ). In

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mucus membrane of the nasopharynx (naso > related to the nose), the

epithelium is respiratory (ciliated pseudostratified columnar) but second and

third parts of the pharynx (oropharynx and laryngiolarynx) and the esophagus all

of them have stratified sqamous epithelium.

Now when we come to the muscles, again we have 2 layers <circular which is

the (inner) and longitudinal (outer)> this is opposite to that in the pharynx >>

longitudinal inner, circular outer (constrictor muscles).

BUT starting from the esophagus downward,

>> circular (inner) AND longitudinal (outer) <<

Type of muscle: Upper skeletal, Lower smooth, Middle mixed

(skeletal & smooth). This figure -refer to the slide- shows the 4 layers of the

esophagus and the type of the epithelium they consist of:

1- In the mucosa, we have stratified squamous epi.

2- In the submucosa, we have mucus glands called esophageal glands.

3- And here (muscle layer), we have inner circular and outer longitudinal.

The last point concerning the esophagus is the superior and inferior

esophageal sphincters. These are not real sphincters; superior at the beginning

and the inferior at the end (where the esophagus opens at the cardia of the

stomach). These are NOT real anatomical sphincters; they are histological

caused by the hypertonia of the muscles at these areas -remember this point-.

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In the animals, the inferior sphincter maybe real anatomical; that's why the

human can do vomiting after eating bad food; this can be done by pushing the

wall of the pharynx or even the posterior one third of the tongue, this leads to

what we called gag reflex, ya3ni elevation of the tongue, the pharynx,

contraction of the stomach and abdominal wall to empty the stomach. While in

animals, this is not possible; ya3ni a rat for example when it eats toxic material,

it can't release this toxic material, this suggests that in the rat there is a real

anatomical sphincter at the lower end of the esophagus BUT not in the human.

The nerve and blood supplies of the esophagus depend on the region, as the

esophagus descends in the neck, chest and the abdomen. So it receives blood

supply from different vessels in each area.

NOW let's move to the abdominal cavity and the anterior

abdominal wall. You know that the abdominal cavity wall includes:

Anterior abdominal wall, posterior abdominal wall, upward we have the

Diaphragm, downward the abdominal cavity continues with the pelvic cavity.

Now, concerning the anterior abdominal wall, it is very important to

remember the layers that form the anterior abdominal wall, so from external to

internal we have:

*Skin (includes epidermis, dermis & hypodermis -fatty layer- which is called

superficial fascia)

*Deep fascia then we have

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*Group of muscles -we will describe them later-. Deep to these muscles we have

another fascia called

*Fascia transversalis, then deep to this fascia we have *Extra peritoneal fat then

we have the

*Peritoneum …. So, these are the parietal layer of the peritoneum because as

you know the peritoneum is a serous membrane; it's formed of -like other

serous membranes such as pleura and pericardium- two layers (parietal & inner

layer). So if we make an incision through this area, for example, we will have

from superficial to deep:

((Skin (epidermis dermis, hypodermis -superficial fascia-) deep fascia

muscles fascia transversalis extra peritoneal fat peritoneum))

Now concerning the nerve supply, the anterior abdominal wall is supplied by

BOTH motor & sensory by the lower five thoracic spinal nerves (this includes # 7,

8, 9, 10, 11, 12) -They seem to be the lower 6 not 5!-. The skin in the abdomen -

as in other parts of our body- is divided into areas called dermatomes. By

dermatome we mean a skin area which is mainly supplied by one spinal nerve;

that's why we called these (dermatomes # 7,8,9,…).

Remember the T10 dermatome is the

dermatome or skin area which

surrounds the umbilicus. Below the

umbilicus we have T11 & T12 and in

the beginning of the thigh we have

L1; this is very important because for

example if somebody lost the

sensation in dermatome T10, this

may indicate lesion in the spinal cord

at T10 spinal segment -this will be

clarified in neuroscience-. Again these

nerves (the lower 5 thoracic spinal

nerves) supply both sensory & motor

nerve supply for the anterior

abdominal wall.

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Concerning the blood supply: Medial side by 2 arteries (one comes from

superior & the other comes from inferior).

The superior one is the superior epigastric artery; this superior

epigastric artery represents the downward continuation or the terminal branch

of an artery coming from the neck and descending behind the sternum which is

the long thoracic or long mammary artery.

The inferior one is the inferior epigastric artery; which is a branch of

the external iliac artery. -You know that aorta at the level of L4, it divides into

right and left common iliac arteries, then each one gives external and internal

branches, internal to the pelvis and external to the lower limbs. From the

external, we have branch goes upward and end in the opposite direction as

inferior epigastric artery.

From the side we have *Intercostal arteries that arise from the thoracic aorta

and **lumbar arteries that arise from abdominal aorta.

Now we come to the VEINS:

Around the umbilicus we have Paraumbilical veins; these veins are connected to

both systemic venous system & portal venous system …

They are connected to the systemic venous system:

1- to the axillary vein by the lateral thoracic

2- to the femoral vein by superficial epigastric

Now when we come to the lymphatic drainage:

** Above the umbilicus, lymph will go to the anterior axillary lymph node.

** Below the umbilicus, lymph will go to the superficial inguinal lymph node at

the beginning of the thigh.

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Lahooooon bikafee ,, tomorrow we`ll begin with the muscles … ya36eeko l-3afyeh

!!!!

Finally done with this tafree`3….

Done by: Hilda Arar, Asma` Jalamneh, Deema 3beidat

عندما ينسج المرء ثياب مذكراته السوداء ويوشحها بالؤلؤ األبيض يبقى هناك خيط مشع يلتصق بثنايا

.الروح لعله الخيط الذي يذكرني بك في لحظات اليأس.

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11/59

4/12

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Anatomy

Abdominal Cavity & Peritoneum

Saleh Bani-Hani

Ehab AL-Masri

Wednesday, 26/10/2011

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This is one of the easiest lectures ever!! Enjoy =D

I added some Pictures and notes form the MSS anatomy lectures to make

this lecture more understandable. And refer to doctor's slide in jam3ye

because it had some written info on it .

Yesterday we started talking about the abdominal wall, and in this lecture we will continuo talking about it, and I hope that we'll have time to talk about the peritoneum. As you know the Abdominal wall from superficial to deep consist of:

1. Skin 2. Superficial fascia(sometimes considered as part of the skin being the

Hypodermis) 3. Deep fascia 4. Muscles 5. Fascia Transversalis 6. Peritoneum

The nerve supply of the anterior abdominal wall (motor and sensory) is provided

by the Lower five Thoracic spinal nerves.

The blood supply : Arteries :

Medial part ..... Superior epigastric (branch of the long mammary A.or

Internal thoracic A. ) and Anterior epigastric .

Lateral part ...... intercostal(posterior) and lumbar artery (branch of

abdominal aorta )

Veins : Above the umbilicus we have veins the radiate form there to connect with both systemic venous system and portal venous system:

Portal ....Paramedian V.

Systemic..... 1. Lateral thoracic V. which connect these periumbilical veins to the Axillary 2. Superficial epigastric which conncect them to the Femoral V.

Lymphatic drainage:

1. Above the umbilicus ........Anterior Axillary 2. Below the umbilicus.........Superficial inguinal LN.

Muscles of the abdominal wall: In the We have four main muscles and a 5th small one .

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figure(1)

The main muscles are: (for more accurate Origins and insertions please refer to text book)

1. Rectus abdominis 2. External oblique 3. Internal oblique 4. Transverse oblique

1.Rectus abdominis :

It's fibers go form Inferior to superior, originating the pubic symphysis and the pubic crest and inserting in the xiphoid process and the costal cartilage form 5-7. When we look at the surface of this muscle we find three fibrous bands there ,we call them tendinous Intersections(figure1),the superior one at the level of the xiphoid process ,the Inferior one at the level of the umbilicus and the median one in between. The lateral border of the rectus abodminis is called linea similunaris,which is really important and we will explain why later.

External Oblique: It originate form the lower 8 ribs and it's fibers run downward and medially , when these fibers reach the lateral part of the rectus abdominis (Linea similunaris ),the

become aponeurosis (a flat tendon) , this aponeurosis run anterior to the rectus abdominis as part of the abdominal wall which we call the rectus

sheath(anterior wall).

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Regarding the insertion of this muscle,it inserts in several areas ,which are 1.Linea alba 2. xiphoid process 3. pubic symphasis 4.and the lower fibers which are related to inguinal Canal and Inguinal hernia . The lower fibers are inserted between the anterior superior iliac spine(ASIS) and the pubic tubercle ,these are very important land marks ,the anterior superior iliac spine represent the anterior end of the what we call the iliac crest, and the pubic tubercle which is located lateral to the pubic symphysis , between these two points (the ASIS and the pubic tubercle) the free end margin of the External oblique becomes thick ,and this is called the Inguinal ligament(figure 2) so the Inguinal ligament is formed by the thinckening of the free lower end of the external oblique between the ASIS and the pubic tubercle.

figure 2 The medial end of the Inguinal ligament turn upward and backward to form what is called arcuate ligament ,which become continuous with the Pectineal liagament (a thickening of the periosteum). Lower fibers insert in the Pubic tubercle and the pubic symphosis, between these two insertions there a gap (no muscles nor apponurosis) ,this gap is called the superficial inguinal ring(figure3), so it's located above and medial to the pubic tubercle.

Internal oblique:

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The fibers are directed from downward to upward (opposite to External),they originate form the 1.iliac crest 2. lateral 2\3 of the inguinal ligament 3. lumbar fascia ,to be inserted in the lower 3-4 costal cartilage ,linae alb and the xiphoid process. The most anterior fibers of the this muscle in the inferior part of the abdomen,which originate form the lateral 2\3 of the inguinal ligament ,make an arch above the medial part of the inguinal ligament to be inserted in the lower linea alba and pubic symphosis ,these fibers join similar fibers of the transverse oblique muscle ,to form what we call the Conjoint ligament, which is located to posterior to the superficial ring supporting it. (Figure(4) )

figure 4 Since we are talking about the lower fibers, we will talk about the Lower fibers of the Transverse Oblique muscle. These fibers orginate from the lateral 1\3 of Inguinal ligament ,and like the internal the also arch to join fibers from the Internal oblique forming the conjoint ligament. So …Lower fibers of internal oblique and Transverse oblique form the conjoint ligament which support the Superfacial Inguinal ring. Back to the apponurosis of the internal oblique,when it reaches the linea similunaris the divide into to anterior and posterior layer running anterior and posterior to the Rectus abdominis , the External Oblique apponurosis goes anterior to rectus abdominis and joins the anterior division of the internal muscle,and finally the transverse apponurosis which runs posterior to the rectus abdominis and join the posterior division of the internal muscle, All these apponurosis meet in the middle to form what we call the linea alba. So linea alba represent the fusion of the apponurosis of the three muscles.

Rectus Sheath: To make it easier I added the information lecture 4 which summarizes what the doctor had said. The rectus sheath consists of two laminae, the anterior sheath and the

posterior sheath. The sheath is made up of the aponeuroses of the three

anterolateral abdominal muscles (external abdominal oblique, internal

abdominal oblique and the transversus abdominis) as they converge at the linea

Alba. The makeup of the anterior and posterior sheaths varies depending on the

level of the abdominal wall you examine.

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The three levels that we will examine are:

above the costal margins: there is only an anterior sheath made up of the

aponeurotic fibers of the external abdominal oblique.

between the costal margin and the arcuate line: anterior sheath is made up of

a combination of the aponeurosis of the external abdominal oblique and the

internal abdominal oblique.

posterior sheath is made up of a combination of the aponeuroses of the internal

abdominal oblique and the transversus abdominis muscles. Notice that the

aponeurosis of the internal abdominal oblique splits around the two sides of the

rectus abdominis muscle.

below the arcuate line: the anterior sheath is made up of the aponeuroses of

all three abdominal muscles.

There is no posterior sheath below the arcuate line. The transversalis fascia

makes up the posterior aspect of the rectus abdominis muscle.

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There is an opening in the transversalis fascia called the Deep inguinal ring,this is located above the inguinal ligament (about 1.5 cm from ) at mid point between the anterior superior iliac spine and pubic symphysis. Between the Deep inguinal ring and the Superfacial inguinal ring we have the Inguinal canal .(figure 5)

figure 5 The Inguinal canal with it's both rings represent a weak area in the lower part of the abdominal wall. Usually the muscle abdominal wall are strong enough to keep the organs within there place ,but sometimes either weakness of these muscle or increased intra-abdominal pressure or even sometimes a congenital error ,might lead to what we call Hernia. What might increase intra abdominal pressure?

- Pregnancy

- Chronic cough

- Tumor, masses

- Pressure during constipation In children the deep inguinal ring is located directly posterior to Superficial inguinal ring, making them a conjoint weak area, but in adult ,with time,the deep inguinal ring move superiorly and lateral to superficial ring forming two weak points, but far away from each other When we describe the anterior and the posterior wall of the inguinal canal ,the anterior wall is made of the apponurois of the external oblique,this wall at level of the deep inguinal is supported by the internal oblique apponurosis. The posterior wall of the canal is made from transversalis fascia and is supported at level of the

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superficial ring is supported by the conjoint tendon. So we have extra support to the weak rings of the canal. In high abdominal pressure usually we do flexion of the thigh,so the contraction of the abdominal wall muscles will give extra support to the weak area.

Hernia : a protrusion of viscera through a weak point in a muscle. 1.Inguinal In the case of Ingunial hernia we have Protrusion fo the peritoneum through the weak point forming Sac, this sac consist of neck and body , one of the important diagnosis of hernia to determine the diameter of the neck, being wide or narrow. If the neck is wide, it is safe ,and the hernia is easy to return to it's normal position ,but if it's narrow it becomes harder to treat, because it's hard to return the hernia to it's normal position. We have two type of inguinal hernia: 1.direct : This affect the mostly older males in the anterior abdominal wall at the level of the conjoint tendon(superficial Ring) ,so we'll have part of the peritoneum pushing the tendon . The neck of this type is wide ,that's why this hernia is safe 2.indirect: Affects the deep inguinal ring, so the peritoneum will go through the inguinal canal,where it stops ,depend on the severity of the hernia ,so it might or might not reach the scrotum. This hernia has a narrower neck making it more difficult than the direct one. Mostly this type is due to congenital disorder and affect the newborns , part of the fetal peritoneum called (processus vaginalis) will push through the deep inguinal ring. Relation of inguinal hernia to pubic tubercle: It's located above and medially to pubic tubercle Constants of Inguinal canal: Male…..Spermatic cord Female….Round ligament of the uterus

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2.Femoral Hernia:

The fascia transversalis will continuo to the lower limb in the thigh as Femoral sheath below the medial part of the inguinal ligament , The femoral sac from lateral to medial will have the the femoral A. the femoral V. and the femoral canal which contain lymph nodes and lymph vessels, the formal N. is located lateral to the femoral sheath ,it is not part of the sheath. The superior end of the femoral canal is called the femoral ring, this ring is located directly below and lateral to the pubic tubercle . This hernia is more common in Females while Inguinal is more common in males.

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3.Umbilical Hernias : (please refer to doctor's slides for pictures ) These are a group of hernias which occur at the umbilical or around it

A. Congenital umbilical hernia: From some reason, part of the mid-gut does not go back to it's original position causing this type of hernia. B. Acquired Umbilical hernia: This occur mostly in infants due to increased intra-abdominal pressure, because the scar at the umbilical cut after delivery, this is safe one and doesn't need treatment. C.Paraumbilibcal hernia: It's an acquired hernia but affect adults, and it is more common in males, from it’s name it does not occur at the umbilicus but around it

4.Epigastric Hernia: It occurs in adult men heavy worker(manual workers),with time they will have a weak area in linea alba in the epigastric area ,so the extra-peritoneal fat will push through this weak are forming the hernia .

11

5,Rectus Hernia:

Diversion of recti due to increase in intra-abdominal pressure and occurs more frequently in Old women with multiple pregnancy (multipara).

5. Incisional Hernia :

Occurs after surgery we might have infalmmationt ,cutting of the never leading to atrophy of muscle supporting the weak areas and so on…

6.Linea similunaris hernia: This hernia has a narrow neck making it hard to deal with because it causes strangulation (small intestines make pressure around blood vessels),it occurs at the level of the Transverse abdominis muscle.

7.Lumbar Hernia : It affects the Lumbar triangle which is surrounded by three structures :

1. external oblique apponurosis 2. Latissmius Dorsum muscle 3. Iliac Crest Weakness in the external oblique and internal causes out push of peritoneal contents.

8.Internal Hernia :

Small concave areas between organs within the peritoneum., this hernia is also characterized by narrow nick, making it difficult to deal with.

12

Thanks to all my friends :D And a special Thanks to Hamze Zaghal:D MALAK:P?? Done By: Ehab Al-Masri

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Anatomy

The Peritoneum

Saleh Bani-Hani

Suha Aqaileh

Thursday, 27/10/2011

25

12 / 59

5 / 12

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Anatomy lec 5: The peritoneum

Thursday, 27-10-2011

Done By: Suha Aqaileh

The figures here are the same as the doctor showed in the lecture, if they aren’t

clear here refer to Anatomy Slides #5! (Also u can find some of these figures colored in

Snell, page (711,713,715,716).

As you know, the walls of our abdomen are lined by fascia. The fascia that lines

the anterior abdominal wall is called fascia transversalis, which is continuous with the

fascia that lines the diaphragm (which is called diaphragmatic fascia), and the posterior

abdominal wall is lined by lumbar fascia and we also have pelvic fascia; all these fascia

form continuous layers that line our abdomen.

3 | P a g e

Deep to this fascia, we have what is called peritoneum. The peritoneum is a

serous membrane, in terms of layers and structure it’s similar to other serous

membranes in our body such as pericardium and pleura, each of these three serous

membranes (peritoneum, pericardium and pleura) is formed of two layers:

1- Outer layer/parietal layer which lines the abdominal wall.

2- Inner layer/visceral layer (serosa) which lines the surface of the organ. (When we

describe the layers of the stomach or small intestine, we say mucosa, sub-

mucosa and serosa, so serosa actually is the visceral layer of the peritoneum that

covers this organ.)

Between them we have a very narrow space called peritoneal cavity, filled with

fluid to allow free movement of certain organs which are surrounded with serosa.

These serous membranes in term of microscopic structure are formed of 2

layers: simple squamous epithelium called mesothelium, underneath this we have a

layer of alveolar connective tissue with blood vessels, and from these vessels we have

filtration of blood plasma to release fluid within the peritoneal cavity called peritoneal

fluid.

The peritoneal cavity in male is a closed cavity, but in female it’s continuous with

the external through uterine tube, uterus and vagina; and through this route, infection

might reach the peritoneal cavity in female.

We can classify abdominal organs according to their location in the peritoneum

into either intra-peritoneum or retro-peritoneum, (when we say intra, we don’t mean

that the organ is present within the peritoneal cavity; because the peritoneal cavity

means the very narrow space between parietal and visceral layer, so within this space

there are no organs we have only very little amount of fluid (150-200 ml)).

When we say intra-peritoneum organs, we mean these organs which are

completely or almost completely surrounded by visceral layer (e.g. stomach, transverse

colon, jejunum, ilium- these organs have free movement). And retro-peritoneum organs

mean these organs which are partially covered by the visceral layer (e.g. duodenum,

pancreas, kidney, ascending and descending colon – these are fixed organs, have a very

little movement) – it’s very important to know the intra and retro peritoneum organs!

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What’s the function of the peritoneum?

1- Allow free movement of certain organs which are surrounded by peritoneum.

2- Carry the blood supply, nerve, lymph to and from the viscera.

3- Limitation (control) of infection: for example, if we have appendicitis or perforated

peptic ulcer, the peritoneum (specially the greater omentum) adheres to the infection

site and tries to limit the infection and prevent the spread of infection. See the next

figure:

A: the normal greater omentum.

B: the greater omentum is attached to an inflamed appendix.

C: the greater omentum is attached to a gastric ulcer.

By looking at a mid-sagittal section: you see the anterior and posterior wall of

the abdomen: (follow the numbers on the next figure with the points below it).

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- (1 - > 2) The parietal layer that lines the anterior wall of abdomen, when it reaches

above in the space between the liver and the diaphragm it will reflect on the surface of

the liver to become a visceral layer.

- (3 - > 4) The parietal layer that lines the posterior wall also when it reaches to the

space between the diaphragm and the liver, will reflect on the surface of the liver to

become visceral layer.

- (2,4 -> 5) the previous two visceral layers will cover the liver downward until they

reach the porta hepatis/hiatus (area of the liver where structures inter or leave the liver

such as arteries, veins, lymphatics, nerves) to form lesser omentum. The lesser

omentum will connect the porta hepatis of the liver and the lesser curvature of stomach

on its right border.

# Generally, Omentum means a fold of peritoneum which connects the stomach with

other organs.

- (5 -> 6) Then these visceral layers will surround the stomach and meet again down at

the greater curvature of the stomach on its left border.

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- (6 -> 7) Then from the greater curvature it will descend downward anterior to the

transverse colon and small intestine, then these 2 layers will turn back upward in front

of the small intestine (jejunum and ilium) until they reach the transverse colon. Here

you see the greater omentum which connects the stomach to the transverse colon and

it has anterior two layers (descending one) and posterior two layers (ascending one) as

you see in the figure.

- (7 -> 8) At the transverse colon, they will divide and cover it, then meet another fold of

the peritoneum called the mesentery of the transverse colon (transverse mesocolon),

this fold will connect the transverse colon to the posterior abdominal wall.

# Generally, Mesentery means a fold of peritoneum which connects an organ with

posterior abdominal wall. Its function is to carry bold vessels to these structures, for

example in the mesentery of the small intestine you will find nerves, lymphatics, vessels

(here it’s the superior mesenteric artery).

- The two layers of the transverse mesocolon, one of them will go posteriorly (9) to

become continuous with the parietal layer of the posterior abdominal wall, while the

other layer will go inferiorly downward (10) to surround different parts of the small

intestine (jejunum, ilium) and this is called the mesentery of the small intestine.

- The space behind the liver, the stomach, lesser omentum and between the two layers

of the greater omentum (ascending and descending one) is called the lesser sac (the

dotted area in the figure), and what remains of the peritoneal cavity is called greater

sac.

Epiploic foramen:

# The greater and the lesser sac communicate with each other through a

foramen (called epiploic foramen / omentum foramen) that passes inferior to the

lesser omentum.

In this figure, the arrow indicates the location of the epiploic foramen / omental

foramen, which presents underneath the hepato-duodenal ligament. From the figure

you can see the borders / surfaces of this foramen:

- Anterior to it: is the hepato-duodenal ligament and lesser omentum (from the book

also the bile duct, hepatic artery and the portal vein).

- Posterior to it: is the inferior vena cava.

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- Superiorly: the gall bladder (from the book also the caudate process of the caudate

lobe of the liver).

- Inferiorly: first part of the duodenum.

Peritoneum ligaments:

# We have several ligaments in the peritoneum - but these ligaments differ in

structure from those of the joints - here the ligament is a fold of peritoneum which

connects the solid organs together or to the abdominal wall, for

example:

- Gastro-phrenic ligament: between the stomach and the diaphragm.

- Spleno-renal ligament: between the spleen the kidney.

- Hepato-duodenal ligament: between the liver and the duodenum.

- Coronary and Falciform ligaments: connect the liver with other structure.

- Gastro-splenic ligament.

8 | P a g e

This figure shows the greater and lesser omentum: you can see the stomach

with its right border (lesser curvature) and left border (greater curvature), again you

see:

- Lesser omentum which connects the lesser curvature of the stomach with the liver at

the porta hepatis and ligament called ligamentum venosum.

- Greater omentum which arises from the greater curvature then descends downward in

front of transverse colon and small intestine then it curves and turns upward to reach

the transverse colon.

# Actually the lesser omentum also connects the liver to the duodenum (the 1st

2 cm of it) by what is called hepato-duodenal ligament (sometimes the ligaments are

part of the omentum), also the greater omentum connected to the 1st 2 cm of the

duodenum.

The hepato-duodenal ligament contains portal vein, hepatic arteries, pile duct,

lymphatics and nerve supply of the liver.

Ligaments related to the liver:

Again in the next section you see the liver, stomach and the parietal layer which

lines the anterior abdominal wall; when this layer reaches the space between the

diaphragm and the liver, it will turn over the surface of the liver to become visceral

layer, this forms the anterior layer of the coronary ligament. The same thing in the

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posterior parietal layer; it also reflects between the diaphragm and the liver to form the

posterior layer of coronary ligament.

The Dr explained it again as following: In the next figure, you see the anterior

surface of the liver: the anterior parietal layer will reflect on the liver forming the

anterior layer of the coronary ligament (on both the right and left lobes) and the

posterior parietal layer also will reflect on the liver forming the posterior layer of the

coronary ligament (on both the right and left lobes), now between the anterior and

posterior layer of the coronary ligament on the right lobe we’ll have what’s called the

right triangular ligament and on the left lobe also between the posterior and anterior

layers of the coronary ligament we will have left triangular ligament.

Between the right and the left lobes of the liver we have another fold of the

peritoneum called falciform ligament which connects the liver to the anterior abdominal

wall.

Bare area: the only part of the liver that isn’t covered by peritoneum, located

between the two layers of the right triangular coronary ligament.

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(Check also Snell, page 776 - figure 20.2, page 777 – figure 20-4 for liver

ligaments).

Recesses /Pouches/Spaces

These are small folds of the peritoneum. If the peritoneum has small spaces /

cavities, then it will make binding there and form this recess (in the slides: recesses are

concavities lined by peritoneum), we have many of them, for example:

- One related to the sigmoid (follow the arrow) in the next figure:

- One at the junction between the ileum and the cecum we have 2 recesses (follow the

arrows) in the figure:

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-We have 4 of these recesses very close to the duodeno-jejunal junction called duodenal

recesses; these 4 recesses are: superior duodenal, inferior duodenal, para-duodenal,

retro-duodenal.

- Below the diaphragm (in the space between the diaphragm and the liver) we have sub-

phrenic recess.

- We have inferior and superior recess of the lesser sac.

Formation of the lesser and greater omentum

The figure below shows the formation of the lesser and greater omentum: in this

transverse section, you see the stomach and peritoneum; we have 2 folds of the

peritoneum related to the stomach:

1- Ventral mesentery: between the stomach and the middle of the anterior

abdominal wall.

2- Dorsal mesentery: between the stomach and the middle of the posterior

abdominal wall.

12 | P a g e

What happened is that between the layers of the ventral mesentery, the liver starts

to be formed in high growth rate so this makes rotation of the stomach, duodenum and

the liver (in the direction of the arrow in the figure), so the liver will move pushing the

ventral mesentery with it; this part of the ventral mesentery between the liver and the

stomach is the lesser omentum. The rotation will move the dorsal mesentery also but

won’t just rotate, it will elongate also.

So the lesser omentum comes from the ventral mesentery while the greater

omentum is formed from the rotation and elongation of the dorsal mesentery.

The peritoneal fluid

We said that the peritoneum is formed of mesothelium (simple squamous

epithelium) and alveolar connective tissue with blood vessels. From these blood vessels,

plasma filtrates out and it goes upward toward the diaphragm because of:

1- Movement of the diaphragm and anterior abdominal wall during respiration.

2- The peritoneal cavity is very thin, so by capillary action (or capillarity) the fluid will go

up.

The fluid goes upward until it reaches the sub-phrenic recess, and there it will be

absorbed by the lymphatics of the diaphragm.

There’s balance between production and absorption; sometimes if there’s

imbalance (e.g. in congestive heart failure or portal hypertension) and no enough

absorption (or there’s higher production rate), the fluid may accumulate in the

peritoneal cavity (that’s what’s called ascites) and by its weight it will go downward.

Also the infection (peritonitis) will form exudate, which is thick and can’t go

upward so it goes down.

So the fluid normally goes upward to the sub-phrenic recess but abnormally (no

absorption/high production/infection) it will go downward.

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In ascites, the patients shouldn’t sleep in a supine position because the fluid will

accumulate beneath the liver and in the pelvic cavity, but we need it to accumulate only

in the pelvic cavity to make it easier and less dangerous (than inserting the needle close

to the liver) to drain the fluid out, and this is achieved by inclined position as in the

figure.

DONE ^^

Special thanks to Basma Deeb and Rasha Al Ebbini :D

GOOD LUCK

0

Anatomy

Histology of the GIS

Qasim Dwairi

Sara alzu’bi

Thursday, 27-10-2011

6/12

13/59

25

1

Anatomy lecture 6

now; In this lecture, we are going to talk about the histology of the GIT, as we all know, the GIS is

divided into: the main organs or channel where the food passes through (from the oral

cavity to the anus) and the accessory organs (liver, pancreas, salivary glands, gallbladder).

All of systems in our body, whether it’s the CVS, renal system, GIS or whatever, are made of

certain components, so we have to understand the basic components and then, we come

to the modifications that occur in different organs. So at the beginning, we’ll discuss the

basic structure then we’ll come to the modifications in every organ of this system.

Basic structure of the GIT The GIT is made of basic layers, these layers are:

Mucosa submucosa muscularis adventitia (serosa) >> from inside toward outside.

; the innermost layer, it’s composed of the lining epithelium and underneath

it; there is loose connective tissue (Lamina propria).

The importance of the lamina propria layer is that it contains the terminal branches of

blood vessels and lymphatics since -as we know- that the epithelium is avascular tissue, so

this layer is important for vascularization.

Abdominal Cavity & Peritoneum

Qasim dwairi

At First, I want you all to forgive me -this lecture was more difficult than a micro lecture!!-, you’ll

notice that the pictures aren’t as the doctor ones, the slides weren’t available & I had to finish it

early in order for you to study it :D so, you have to look at them… some slides the dr. went over

them and said that we have to know this and that…

The dr. was mixing between things, so for those who attended the lecture, they’ll notice that it’s

not as the arrangement of the dr. himself… but be sure that it contains all the things the dr. said.

Also, you’ll see some additions from the book (junqueira histology) in areas or points weren’t

discussed appropriately…

The dr. said that he’ll write the exam from the lecture’s TOPICS (w allaho a3lm!! )

Thank you my sister rama… allah y36eke el 3afye 3l tfre3’ wl revision… w hadeel kofahi 3l revision w

thanks ele 5letk tdrose ;)

2

; loose aerolar connective tissue (in the book: DENSE CT!!), underneath

the mucosa layer.

We know that most of the organs of the GIS are collapsible

organs, means that they are not opened all the time and the bolus of

food has to pass, so it will exert pressure on the wall of the tube, so

this CT is the best to adapt that pressure.

It contains the major blood vessels & certain mucous or serous

glands for the lubrication of the bolus during its passage through

the tract after swallowing in the esophagus so it helps the peristaltic

action for movement of the bolus.

So the submucosa is a connective tissue that contains major blood vessels and lymphatics with

certain plexuses of nerves & submucosal glands.

; Underneath the submucosa, there are 4-6 layers of smooth muscle.

The smooth muscle is arranged into: Inner circular and outer longitudinal, so during

contraction & relaxation, the circular one will be wider or narrower and the longitudinal

one will be shorter or longer, and that’s how the peristalsis movement occurs.

The importance comes from the presence of glandular secretions throughout the GIT,

so we need something to assist the squeezing of these secretions into the lumen so this is

the function of muscularis mucosa.

Also, we know that the GIS is folded inside, it’s thrown in different folds (discussed

later), and the muscularis layer (also the muscularis mucosa) plays an important role in the

different folding of the GIT.

So, the muscularis layer is important for squeezing the secretions & helping in proper folding of the

GIT & propel the food within it.

BOOK:

There is a layer called muscularis mucosa layer, between the lamina propria (or mucosa)

and Submucosa… consist of inner circular & outer longitudinal smooth muscle >> it’s

different from the muscularis layer (externa) that’s present between the Submucosa &

adventitia.

Between the 2 smooth layers in muscularis mucosa, there’s connective tissue contains

vessels, nerves & lymphatics.

Remember that the

definition of CT is a tissue

that brings up different

tissues in our body.

Every tissue in our body is

surrounded by some layer

of CT. so then the mucosa

is surrounded by a CT

which is the Submucosa.

3

it’s the outermost layer; adventitia: when the outer layer of the

organ is not associated with the peritoneum. While if it’s present within the abdominal

cavity, we call it: serosa.

Modifications in the layers along different organs of the GIT

Generally; it starts with keratinized stratified squamous epithelium at the lips, and then as

we move in the vestibule of the mouth, there will be transition gradually, not abruptly, of

the epithelium…

Do we need keratin in the oral cavity?!

Yes. Logically, wherever there’s a direct contact with the food stuff, we need a

protection in the form of keratin. So in the: gingiva, tongue & hard palate >>

there would be keratinized squamous epithelium & the rest of the oral cavity is

going to be NON-keratinized stratified squamous epithelium.

In the pharynx, we have 2 parts; nasopahrynx lined by respiratory epithelium

(pseudostratified columnar epithelium) & the oropharynx which is lined by stratified

squamous epithelium.

In the esophagus >> also stratified squamous epithelium.

4

In the stomach, small & large intestines >> simple columnar epithelium till reaching the

ano-rectal junction where the lining will be reversed back into stratified squamous

epithelium & then keratinized stratified squamous epithelium.

Look at the lips in the section on

the left; you see deposits of

keratin (arrowhead), and the

stratified squamous epithelium,

while the other oral mucosa as

you can see is just stratified

squamous epithelium.

We can differentiate the keratinized from non-keratinized

by Keratin, which is Acellular, so, we don’t see nuclei, just

fibers, so even if the color of the stain changed, don’t get

confused, whenever you see fibers without nuclei, this is

keratinized epithelium.

Keratinized

stratified

squamous

epithelium

(lips, tongue,

hard palate,

gingiva)

Non-Keratinized

stratified

squamous

epithelium

(vestibule & other

parts of the oral

cavity)

Pharynx

Nasopharynx:

pseudostartified

epithelium

Oropharynx &

esophagus: Stratified

squamous

epithelium

Stomach, small

intestine & large

intestine: Simple

columnar

epithelium

Lower anal canal

& anal orifice:

Keratinized

stratified

squamous

epithelium

Ano-rectal

junction & upper

anal canal: Non-

Keratinized

stratified

squamous

epithelium.

1- Lips & oral cavity

Epithelium

5

Look at the lining epithelium in the esophagus, we just

have stratified squamous epithelium, the lamina propria

have no modifications (lamina propria of the lower

esophagus near the stomach have mucous secreting

glands called esophageal cardiac glands (small arrow),

book).

In the submucosa, we have glands, or a group of acini of

glands, we call them: submucosal glands and of course

we see different layers; inner circular and outer

longitudinal muscles in the muscularis layer (externa).

The arrowheads represent muscularis mucosa.

The glands are classified based on the arrangement of cells!!:

If the cells surround a central lumen, this is acinar.

If they are in the form of tube, they are tubular.

If the lumen is large, we call them alveolar.

Again in the stomach, we see simple columnar epithelium, and

it’s going to be in the form of pits (arrows). So when we reach

the stomach, we see the folds of the stomach or invaginations

called pits (or foveolae); as a bottle, so it has an isthmus, neck

and base >> this is exactly what the dr. said.

In the book: we have in the lamina propria a branched tubular

gastric glands (2 headed arrows) that open into the bottom of

the gastric pit, each gland has 3 distinct regions: neck, isthmus

& base, these gland are discussed later.

2- Esophagus

3- stomach

Sub

mucosa

6

In the small intestine, the mucosa is in the form

of villi (a) (they are projections of mucosa into the

lumen) and the purpose of these villi is to

increase the surface area of absorption, and on

the columnar cells, we have microvilli (b), in each

columnar cell of the small intestine, the number

of microvilli could be up to 2000 and they

increase the total surface area by 20 folds, so

wherever you expect absorption, you have to

have microvilli (as in renal tubules of kidney

-for example- where we have filtration of the blood then we have selective absorption).

Also, we have ring-like structure mucosal arrangement in the intestine which is due to what

we call plica circluaris; that’s in the whole mucosa thrown into these circular folds.

The lining of the small intestine shows a series of permanent folds, plica

circularis (kerckring’s valves), consisting of mucosa & submucosa and having

semilunar, circular or spiral forms. They are well-developed & a characteristic

of the jejunum, they don’t constitute a significant feature of the duodenum &

ileum.

Intestinal villi are long outgrowths of the mucosa (epithelium + lamina propria)

projecting into the lumen of the small intestine.

Between the villi are small openings of simple tubular glands called intestinal

glands (also called crypts or glands of Lieberkühn), they also present in the

large intestine

At the apex of the epithelial cells, there is a layer called brush (striated)

border & this border is seen to be a layer of densely packed microvilli.

< Plica circularis, villi, microvilli >> increase the surface area of the intestine >

4- Small intestine

circ = inner circular muscle

layer of muscularis externa

cr = crypt

pl = plica circularis

subm = submucosa

V = vill

To differe-ntiate:

Crypts, intestinal glands

7

Now, the maximal absorption takes place in the jejunum so the difference

between the duodenum & ileum & jejunum is that there are more and

longer microvilli in the jejunum.

Large intestine, the lumen is here instead of villi projections upward, we see

invaginations downwards. And what we call: crypts of Lieberkühn. (although they

may present in the small intestine)

Another thing you observe in the

lining epithelium, we see light

mucous secreting cells (goblet cells,

between the epithelial cells near

the lumen), because by the time the

food has reached the large

intestine, maximal absorption will

take place, because the food

solidifies, it needs more lubricants

to pass through,

so as we move down, we expect to see an increase in the number of

mucous secreting cells. And because it’s a mucus, the mucus is

polysaccharides & during histological preparations, the mucus is

extracted (that’s why we see the cytoplasm of the adipocytes empty),

And here is the same thing so they appear as white circles.

jejunum

5- large intestine

Crypts or glands

of the large

intestine.

BOOK: the large intestine consists of

mucosal membrane with no folds except

in the distal (rectal) part.

The intestinal glands (crypts of

Lieberkühn) are long and characterized by

a great abundant of goblet cells.

also, the epithelium has a microvilli on

the apex.

cr = crypt or gland

g = goblet cell

LP = lamina propria

lu = lumen of gland

n = nuclei of epithelial cells of gland

arrow = striated border of absorptive cells

asterisks = boundary between 2 adjacent

glands

8

After the last part of the large intestine, we have the rectum (the dr. didn’t say any thing

about it) then the anus.

Now, this is the transition at the ano-rectal junction, so

we see crypts of Lieberkühn and then the crypts are

absent, and there will be stratified squamous

epithelium.

The mucosa in the anal canal are thrown into

longitudinal folds and these columns of the anal canal

are called columns of Morgagni (arrows), so if you are

asked where are the columns of Morgagni then you

will answer they are the longitudinal folds of the

mucosa that present in the anal canal.

Here, we finished the modifications in the mucosa, or the epithelial lining, now talking about the underlying

layer which is the lamina propria.

The lower part of esophagus near the stomach have mucous secreting glands called

esophageal cardiac glands.

** The stomach is divided anatomically into:

cardia, the fundus, the body, the pyloric region

(canal & antrum).

> the fundus region is located above the junction

of the esophagus, and it’s anatomically related to

the site of apex beat, that’s why, there are many

cases when a patient has gastritis or ulcer, and

Upper part,

presence of

crypts

Absence of

crypts,

stratified

epithelium

At the anal

orifice;

keratinized

squamous

epithelium

6- Ano-rectal junction& anus

9

there’s a production of gas, the gas hits up at the fundal part [because gases go up] and

there’s a referred pain that’s why the patient will feel an acute pain at the left side and he’ll

think that he’s going to have a heart attack, so we should consider the possibility that the

pain the patient is suffering from is due to ulcer or gastritis and it has nothing to do with

the heart itself.

In the lamina propria of the stomach, we have what we call gastric glands, now, different

regions of the stomach have different types of glandular cells;

The glands underneath (or can be within) the pits, they open into the bottom of it, each

gland has 3 distinct regions: neck, isthmus & base.

Cells within the glands, or glandular cells are:

Goblet cells or mucous cells, secrete Mucus or mucin, present in the neck of the gland.

Chief cells; which secrete digestive enzymes; pepsinogen & lipase, take basophilic

stain & are present in the base of the gland.

Parietal cells (oxyntic); that secrete the HCL & intrinsic factor, rich in carbonic

anhydrase, take eosinophilic stain & present in middle somehow.

Some endocrine cells; G cells that secrete gastrin.

We have also enteroendocrine cells in the neck and base in the fundus and body of

stomach, while in the pyloric region, they are intercalated with the mucous cells

(called here G cells or D cells).

> Different endocrine cells in different regions of the tract secrete different substances

>We have different stimuli affecting or regulating the secretion, you should be taking

that in anatomy.

10

3- :

In the small & large intestines: we know that the lamina propria is the closest layer to the

surface epithelium.

We know that we have a lot of bacteria and

microorganisms along the GIT, so we have

aggregates of lymphoid tissue within the lamina

propria called GALT (gut associated lymphoid

tissue) or peyer’s pathches, they are present in the

appendix (of large intestine) and in the ileum (of

small intestine).

>> so if you are asked, peyer’s patches

concentrated where, you’ll answer that they are

concentrated in the ileum and in the appendix.

Appendix is a blind diverticulum, narrow lumen,

and the most characteristics of it is the large

aggregates of lymphoid tissue & it has a good

single blood supply, it’s a critical factor that’s

involved in so many pathological conditions,

whether ischemia or total blockage of blood, in

heart or hernia, certain fecal stuff get stuck over

there so it’s a proper media for microorganisms

growth, infections & inflammation, so activation of

lymphoid tissue and accumulation of inflammatory

fluid so pressure on the single blood supply, cut of

the blood, necrosis >> this is appendicitis.

The bacteria may pour to the peritoneal cavity, and that’s why

it’s considered as emergency.

So, there are 3 types of cells:

- Mucous neck cells in the

neck of the gland.

- Parietal cells, in the middle

& stained by eosinophilic

stain (arrows).

- Chief cells, in the base and

stained by basophilic stain

(arrowheads).

Again and again and again……

The intrinsic factor, that’s secreted by the parietal cells, it’s related to the deficiency of Vitamin B12,

and causes the pernicious anemia.

11

So, the modification of the lamina propria >> the accumulation of lymphoid tissue, and

these are the lymphoid follicles and inside you see the activation centers that contain a

background of reticular tissue that divides it into the compartments filled with the

lymphocytes, so you see large population of lymphocyte and here where the lymphocyte

actually mature (we mean by mature that they are produced in the bone marrow then they

go to the lymphoid tissue and there, They are trained to recognize what self and what is

foreign and this cell after it become specialist in recognizing only a single antigen, it forms

memory cells, if it sees this antigen again it will form the Ab, and when they become

mature to form Ab we call them plasma cells).

Modifications in

It is a connective tissue that contains large vessels, lymphatics and nerves, we have also

submucosal glands.

Throughout the tract, there are no major changes… the most important to talk about is the

duodenum:

In the duodenum, we have large aggregates of

submucosal glands; we call them brunner

glands, you see all these aggregates in the

submucosa.

So, in a microscopic slide, in the

submucosa, if we have large aggregates of

submucosal gland, immediately you will say

this is duodenum, in addition to the

presence of villi (in the mucosa; part of

small intestine).

Starting from the esophagus moving downward, we have two layers: inner circular and

outer longitudinal, but we said there are certain modifications taking place:

1- The esophagus:

We know that the esophagus is divided into 3 parts; upper, middle & lower.

12

When we eat something, the beginning of the process of swallowing, we have a certain

control, that’s why when you do gastroscopy, the problem by introducing the tube is in the

beginning & after it passes the upper third, it will be automatically swallowed.

So, the muscles that present in the esophagus;

The upper portion, exclusively skeletal muscles.

The middle third contains a combination of skeletal and smooth muscles

The lower third is exclusively smooth muscles

2- The stomach:

Firstly, the stomach is not tube-like structure, instead, it’s J-shaped so it has to move in

more than one dimension, it has inner circular, outer longitudinal muscles (the axis of

movement is linear) but the stomach has to mix the food with the gastric secretions, so it

has to move in different axises, more than one axis, so we need an additional layer of

smooth muscle and that would be the oblique layer..

Secondly, through the GIT, we come across certain places called valves; we have the gastro-

esophageal valve, pyloric valve and the ileo-cecal valve, these valves are described as

functional or anatomical.

- Gastro-esophageal functional valve

- Pyloric & ileo-cecal anatomic valve

What’s the difference between a functional and an anatomical valve?

The functional (gastro-esophageal) is under the control of autonomic nervous

system, there is no structural difference, no obvious structure, while the

anatomical valve like in the pyloric and the ileo-cecal, the inner circular muscle is

thickened.

So the second modification that happens in the valve is the thickening of the inner

muscular coat.

This is the pyloric

sphincter; of course

we have the

thickening of the

circular layer.

13

3- small intestine: No major modifications, but we have the ileo-cecal anatomic valve > thickening of the

circular layer.

4- Large intestine:

In the large intestine, we have three slips of the outer longitudinal coat, and these slips are

attached on the wall (may be the abdominal wall), I want you to imagine that this is a long

tube, and we have three points of attachment of these slips to the coat and that what gives

the large intestine the sausage-shape >> these are what we call: the tenia coli.

So, this is the slip of muscle as we see, started at the circular towards the serosa.

>> So, the modification that happened in the muscular layer: thickening of the inner circular

to form anatomical valves, and three slips (tenia coli) on the outer circular in the large

intestine.

Concerning the serosa or adventitia:

The abdominal part of esophagus covered by serosa while the other parts are covered by

adventitia (CT). and the other parts of the GIT covered by serosa which is part of the peritoneum.

here, the dr. started to move on the slides quickly… so you have to look at them

He showed a slide that contains the surface markings and

said that it’s very important, if we haven’t taken it in

anatomy, he want us to study it carefully.

Another slide shows the gastroctopy, and the tube that

they use, there are measurements on it, but as doctors, you

circ = inner circular layer

CT = connective tissue separating

circular and longitudinal muscle

layers

long = outer longitudinal layer

TC = part of a tenia coli

14

have to know the distance from the external nerves till where we reach, we have to know where

it is.

- The distance from the external nerve to the cardiac orifice is 44 CMs.

- From the cardiac orifice to the pylorus part, we have 15-25 CMs.

** We have to know these distances, they are written on the tube, but you have to know since you

are a doctor, So, how much are you going to keep pushing the tube inside the body, You have to

know when to stop.

Talking about the ulcer:

The ulcer: a very common condition, in the

stomach and in the duodenum.

The ulcer is disruption of the normal mucosa, we know

that there are mucous secretory cells, in the neck and

the fundus of the stomach, they secrete mucus, and

this mucus adheres firmly to the underlying epithelium

and creates a barrier between the gastric secretions

and the lining epithelium.

It’s Due to some conditions; stress, physiological, psychological, spicy food.. etc.

Causes of gastric ulcer; they say at first it’s because of spicy food and caffeine, but two

scientists in 1982 from Australia discovered that there is a type of bacteria that’s responsible for

causing the gastric ulcer, which is H. pylori, and they changed the whole process of treating

gastric ulcers, those two spent 12 years to convince the scientists that H. pylori is the cause of

the ulcer, and eventually they won the Nobel prize.

Another slides and said: We talked about the referred pain and the relation of the celiac plexus

in anatomy, it goes from T5 to T9, so it’s referred to the chest wall.

The end

Lolololoeeeeeessshhhhhh

it’s

1

18/59

7/12

45

Anatomy

Anatomy of solid organs of GIT

Saleh Bani-Hani

Tariq Kewan

Monday, 31/10/2011

2

بسم هللا الرحمن الرحيم

Subject : Anatomy lec # 7.

Done by: Tariq Kewan.

Revision

As you know the peritoneum is formed by parietal layer and visceral layer, the

parietal layer covers the abdominal and the pelvic walls, the visceral layer covers

the organs. In fact the serosa, which is the fourth layer in the wall of these organs,

is the visceral layer of the peritoneum. Between these two layers we have very

small space called peritoneal cavity (or peritoneal space), which contains a very

thin layer of fluid (the peritoneal fluid). There is no organs lie within or inside this

fluid or space.

Due to the folds of the peritoneum, some of the organs are completely covered or

surrounded by the visceral layer. These called intra-peritoneal organs.

# Examples: stomach, liver, transverse colon, sigmoid colon, appendix.

In the other hand, some of the organs are partially covered by the visceral layer.

These called extra-peritoneal or retro-peritoneal organs; because most of them

are located at the posterior abdominal wall (behind the peritoneum).

# Examples: duodenum (except the initial 2 cm), pancreas.

The peritoneum has many functions:

# It facilitates the movement of the organs, especially these organs that are

located within the peritoneal cavity (intra-peritoneal organs). In the other hand

the retro-peritoneal organs are usually fixed in their positions.

For example the duodenum, ascending and descending colon have a limited

range of movements.

3

# The folds of the peritoneum, such as the mesentery, contain blood vessels,

nerves, lymphatic vessels, which supply these organs.

# In the case of infections (like: appendicitis and perforated peptic ulcer) part of

the greater omentum will adhere to these infections to limit the spread of these

infections. (figure 4)

The peritoneal cavity is divided by these folds of the peritoneum into two sacs:

-Lesser sac .

-Greater sac.

#now you should know what we mean by these folds:

Mesenteries: are two-layered folds of peritoneum connecting parts of the

intestines to the posterior abdominal wall.

Examples:

Mesentery of the transverse colon will connect the transverse colon to the

posterior abdominal wall.

Mesentery of small intestine will connect the jejunum and ileum (but not

duodenum) to the posterior abdominal wall.

Again they contain blood vessels and nerves that supply these organs.

Omenta: are two-layered folds of peritoneum that connect stomach to other

organs.

The lesser omentum: connects the stomach to the liver.

The greater omentum: starts from the left border of the stomach (the greater

curvature) and descends as a double layer in front of the transverse colon and

then in front of the jejunum and ileum, after that it will curve up again. Now even

this posterior layer of the greater omentum will ascend anterior to the small

intestine (not posterior). When the ascending layer reaches the transverse colon,

4

one layer will go anterior to the transverse colon and the other layer will go

posterior to the transverse colon and it will fuse with the mesentery of the

transverse colon.

Note: both the anterior (descending) layer of the greater momentum and the

posterior (ascending) layer of the greater omentum are anterior to the small

intestines. Look at figure one.

Lesser sac

Space located behind the liver, lesser omentum, stomach and between the

descending & ascending layers of the greater omentum.

We divide the lesser sac into superior recess and inferior recess. (figure 1).

Figure 1

Superior

recess

inferior

recess

5

Here we have the mesentery of the small intestine (jejunum and ileum) and the

mesentery of the transverse colon (transverse mesocolon) which connects

between the transverse colon and the posterior abdominal wall. (figure 1).

Here you can see the pancreas as example of the retro-peritoneal organs. (figure

1).

The duodenum also is another example of the retro-peritoneal organs. (figure 1).

Note: The space of the greater and the lesser sac appears very large but actually

they are very thin spaces.

# Again, there are no organs lie within the peritoneal cavity or space, only thin

layer of peritoneal fluid.

This is the stomach, and you can see the lesser omentum and the greater

omentum. (figure 2)

The Falciform ligament extends from the umbilicus to the liver, it attaches the

anterior surface of the liver to the anterior abdominal wall and the superior

surface of the liver to the diaphragm . The free margin of the falciform ligament

contains what we call ligamentum teres or the round ligament of the liver, this

Figure 2

6

ligament is not actually a fold of the peritoneum like the falciform ligament ,

however it is the remaining part the umbilical vein ; in the embryo the oxygenated

blood is carried to the liver by the umbilical vein , after delivery the remaining

part of the umbilical vein will obliterate and become fibrous tissue and forms

what we call the ligamentum teres .

So the falciform ligament is fold of the peritoneum but the ligamentum

teres is not.

The Dr said that it is better to see the liver ligaments and understand them in the

practical.

This figure (3) shows the boundaries of the foramen that connects the lesser sac

and the greater sac, we call it omental foramen or epiploic foramen .

The right border (or the free border) of the lesser omentum connects the liver

with the pylorus and the first one inch of the duodenum and that’s why we call

this part hepato-duodenal ligament.

The foramen will be underneath the free margin of the lesser sac (the hepato-

duodenal ligament).

Anteriorly : hepato -duodenal ligament .

Figure 3

7

Posteriorly : inferior vena cava .

Superiorly : liver and gall bladder .

Inferiorly : duodenum .

As we said in the case of infections the greater omentum will adhere to the sites

of infection (appendictitis or perforating peptic ulcer) to prevent or limit the

spread of these infections.(figure 4)

In the case of ascites (or presence of large amount of fluid within the peritoneal

cavity) the supine position of the patients is wrong and should be avoided;

because it allows the fluid to accumulate underneath the liver (which is not good).

Figure4

Figure5

8

We want the fluid to accumulate or to be within the pelvic cavity so we can

remove it safely and avoid the liver. This can be done by sit the patient in the

inclined position rather than the supine position. (figure 5).

So whatever the cause of the ascites ( congestive heart failure or infection) we

should avoid the supine position.

The abdominal cavity and the organs within it

We use two ways to divide the abdominal cavity :

The first way

We divide the abdominal cavity into four quadrants (upper right, upper left, lower

right, lower left) by two lines:

Vertical med line that passes through the umbilicus

Horizontal line that also passes through the umbilicus. (figure 6)

Figure6

9

The

secon

d way

We divide the abdominal wall into nine regions (figure 7) by two vertical lines and

two horizontal lines.

The vertical lines ( mid-clavicular):

Downward it will pass through the midpoint between the anterior superior iliac

spine and the symphisis pupis (here we can find also the deep inguinal ring).

Remember: deep inguinal ring of the inguinal canal is located .5 inch above the

inguinal ligament at the midpoint between the anterior superior iliac spine and

the symphisis pupis .

The horizontal lines:

# The first one will pass through the lowest point of the costal margin, which is

made by the costal cartilage of the rib number 10 not by the rib number 12 .

Figure6 Figure7

10

Note: The costal margin is made from the costal cartilages of the 7th, 8th, 9thand

10th ribs.

This line is called sub-costal line because it passes along the lowest point of the

costal margin, which is made by the rib number 10. It locates at the level of L3.

#The second horizontal line will pass between the two tubercles of the iliac crests

and it locates at the level of L5 vertebra.

This line is called inter-tubercular line or trans-tubercular line. Locations of some

abdominal organs : (figure 6 )

The stomach is located in the epigastric region.

The Transverse colon is located in the umbilical region .

The liver is located in the right hypochondriac and the epigastric regions .

Stomach

Figure8

11

General description :

The first part of the stomach is cardia , which is the small part that surrounds the

lower esophageal opening , here we have the fundus (figure 8) , the body and the

pylorus . The pylorus consist of the pyloric antrum , pyloric canal and surrounded

by the pyloric sphincter .

At the junction between the body and the pyloric antrum we have an angle called

incisura angularis.

Concerning the surfaces, the stomach has anterior surface and posterior surface,

when we come to the borders, we have very large left border which is also called

greater curvature and we have right border which is also called lesser curvature.

Peritoneal covering :

Again the lesser omentum connects the lesser curvature and the first 2 cm of the

duodenum with the liver while the greater omentum connects the greater

curvature and the first 2 cm of the duodenum with the transverse colon. So the

first two cm of the duodenum are included with the stomach in the lesser and the

greater omentum (intra-peritoneal). Otherwise the rest of the duodenum is rid of

peritoneum.

Histology :

We know that the muscularis in the gastro-intestinal tract is formed of 2 layers of

muscles; internal circular and external longitudinal.

In the stomach (because we need stronger wall; for stronger movements to mix

the food with the gastric acid very well) we have additional layer internal to the

circular layer called oblique layer.

So the muscularis of the stomach consists of three layers from inside to outside:

Oblique circular longitudinal. (figure 8).

The pyloric sphincter is anatomical and physiological sphincter . And we should

explain what we mean by anatomical and physiological sphincter:

12

*Anatomical sphincter: the circular muscles at this area are thicker than the

muscles in the remaining areas of the stomach, so thicker than normal.

*Physiological sphincter : here the thickness is normal or similar to the other

parts but the muscles at that part are in continuous contraction (hyper-tonia) .

Anatomical thicker fibers.

Physiological Hypertonic fibers.

Anatomical and physiological (as the pyloric sphincter) thicker and

hypertonic fibers.

What is the function of the pyloric sphincter??

It will control the movement of the food from the stomach to the duodenum.

The relation of the stomach :

*Anteriorly : liver ,sub-costal margin , diaphragm (which separate the stomach

from the base of the left lung ) ,(figure 9 ).

Figure9

13

*Posteriorly :

All the structures that lie posterior to the stomach will form what we call the

gastric bed or stomach bed and they includes:

Lesser sac (as space), spleen, pancreas (body and tail msinly), left kidney, left

supra-renal gland, splenic artery (along the superior border of the pancreas), part

of the diaphragm and part of the transverse mesocolon , (figure 10 ).

location :

Mainly in the epigastric region, (figure 6)

Figure 10

14

Small intestine

It is formed of duodenum , jejunum and illium . it’s length exceed more than six

meters .

Duodenum

General description :

-The duodenum consists from 4 parts.

-The duodenum has a C –shape structure and it starts from the first part after the

pylorus of the stomach and then move to the right and upward, then the 2nd part

will descend vertically until the begging of the 3rd part which will turn to the left in

the horizontal line . The 4th part will turn to the left and upward, (figure 12 ,11).

This C-shape structure will receive the head of the pancreas inside it.

The bile duct will arise from the liver as left and right hepatic ducts; these will join

each other to form the common hepatic duct which receives the cystic duct from

Figure 11

Figure 12

15

the gall bladder to form the bile duct. The bile duct will descend behind the first

part of the duodenum to join the pancreatic duct, which carries the pancreatic

secretions, to form what we call the hepato-pancreatic ampula or ampula of

vater, which will open into the 2nd part of the duodenum. When this ampula

opens to the duodenum it will make elevation of the mucous membrane, this

elevation called major duodenal papilla. Before the orifice we have sphincter

which consists of smooth muscles surrounding the opening of the ampula , this

called sphincter of oddi. (figure 13).

Peritoneal covering :

Only the very begging part of the duodenum is related to the peritoneum. The

greater and the lesser omenta are attached only to the first 2 cm of the first part

of the duodenum. The other parts are not covered by the peritoneal cavity.

The relation of the duodenum : (figure 11)

*Anteriorly :

1st part : liver and gall bladder .

Figure 13

16

2nd part : liver, gall bladder and the transverse colon

3rd part : part of the jejunum , part of the mesentery of the small intestine ,

superior mesenteric artery .

4th part : the jejunum only .

*Posteriorly :

1st part : inferior vena cava , portal vein , bile duct .

2nd part : the right kidney , right ureter.

3rd part : inferior vena cava , aorta.

4th part : left margin of aorta and medial border of psoas muscle.

The most important relation to the duodenum is the head of the pancreas which

impeded within the C-shape of the duodenum.

Jejunum and Ilium

The length of the jejunum is about 2.5 meters and the length of the ileum is about

3.5 meters.

Figure 14 Figure 15

17

The jejunum is located in the upper left part of our abdominal cavity just below

the transverse colon while the ileum is located in the lower right part of our

abdominal cavity and it reaches the pelvis. (figure 14)

The mesentery of the jejunum will connect it to the posterior abdominal wall and

attach to the posterior abdominal wall just to the left of the aorta while the

mesentery of the ileum attach to the posterior abdominal wall just to the right of

the aorta.

Comparison between jejunum and ileum:

The jejunum has wider lumen, thicker wall, and has more plica circulares.

We know that one of the main functions of the small intestine is the absorption of

food, that’s why we need modifications to increase the surface area of the small

intestine, actually there are three modifications:

# Transverse circular folds of mucosa and sub-mucosa called plica circularis ,

these are much more in the jejunum than in the ileum, and that will make the

wall of the jejunum thicker than the wall of the ileum .

# Villi : are microscopic structures , not macroscopic like the pllica circularis .

# Micro-villi.

We have more lymphoid tissues in the ileum and they are very large, we call them

payer patches.

diameter Thickness of wall

Plica circulares

Lymphoid tissue

Jejunum wider thicker more less Ileum narrower thinner less more

18

Large intestine

General description :

It is formed from cecum (which receives ileum) , ascending colon , transverse

colon , descending colon (will enter the pelvis) , sigmoid colon which starts at the

pelvic brim , just anterior to S1 and continues in front of the first and the second

sacral vertebra , at the level of S3 vertebra it becomes rectum. The length of the

rectum is about 13 cm and it descends in front of S3, S4, S5 and the coccyx bone

then it will penetrate the pelvic floor to become the anal canal.(figure 16 ).

Concerning the length of the large intestine, it is more than 1 meter.

Histology :

When we look at the large intestine, it is very easy to find the macroscopic

features and differences between the large intestine and the small intestine. The

large intestine has what we call haustra which appears like swellings in the

mucosa. In the small intestine the longitudinal muscles cover the whole wall of

the small intestine but in the large intestine the muscle fibers become less in

Right colic flexure left colic flexure

Figure 16

19

number and they will be organized in three bundles that we can see on the

surface, we call these bundles tinea coli.

So tinea coli are bundles of the longitudinal muscle fibers of the large intestine.

Also we can see what we call appendix epiplocia( زوائد دهنية ) attach to the surface

of the large intestine . (figure 17)

Locations and peritoneal attachments of different parts

Cecum

Cecum is located in the lower right iliac fossa, it receives the terminal part of

ileum and here we have what we call ileuo-cecal sphincter that controls the

movement of food from the ileum to the cecum. when large amounts of food

passes to the cecum , the wall of the cecum will distends and sends negative feed-

back signals to the wall of the ileum to prevent more peristalsis ,these signals will

control the ileu-cecal sphincter also , to prevent movements of more food from

the ileum to the cecum .

When the ileum opens into the cecum it will make a fold in the mucous

membrane of the cecum this is called ileuo- cecal valve. We should differentiate

between sphincter and valve; sphincter is composed of circular smooth muscles

but the valve is only a fold of the mucous membrane which surrounds the orifice

or the opening.

Figure 17

20

The terminal ileum will open into the cecum at the junction between the cecum

and the ascending colon.

#length: about 6 cm.

Appendix

Attaches to the cecum at its poster-medial aspect (figure 18) and because it has a

mesocolon it will have a good free movement, that’s why when they try to

position the appendix in surface anatomy, they describe the position of its base

not its tip or apex; because the apex can move.

The base of the appendix is located about one third the distance of the imaginary

line that connects the anterior superior iliac spine and the umbilicus. This point is

called Mc’Burney’s point. (figure 19 )

# Length: about 2.5 cm.

Ascending colon

It ascends from the secum upward to the liver, just lateral to the right vertical line

(mid-clavicular) . The peritoneum covers only the anterior surface and the sides of

the ascending colon so it is a retro-peritoneal organ.

#Length: about 13 cm.

Figure 18 Figure 19

21

Transverse colon

The ascending colon will curve to the left to make the right colic flexure which is

located just below the liver so we call it also hepatic flexure.

Then it will make the transverse colon which will go horizontally to the left in the

umbilical region. Below the spleen the transverse colon will turn at the left colic

flexure or splenic flexure and forms the descending colon.

The left colic flexure is connected to the diaphragm by a ligament (which is a part

of the peritoneum) called phreni-coloic ligament, to fix this part of the transverse

colon in its position . (figure 20)

# The hepatic flexure and the right kidney are located at lower level than the

splenic flexure and left kidney; because the liver will push the right colic flexure

inferiorly.

# The transverse colon is completely surrounded by the peritoneum (by the

greater omentum and transverse mesocolon)

#Length : about 38 cm.

Descending colon

From the splenic flexure the descending colon will descend just lateral to the left

vertical (mid-calvicular) line. It will descend until it reaches the pelvic brim where

it becomes sigmoid colon. Like the ascending colon, the peritoneum covers only

the anterior surface and the sides of the descending colon.

Phreni-colic

ligament

Figure 20

22

#length : about 25 cm.

Sigmoid colon

Is located in the pelvis and extends from S1 to S3 vertebrae , where it becomes

continuous with the rectum. The sigmoid colon is completely covered by the

peritoneum.

Rectum

Its length is about 13 cm, and it passes through the levator ani muscle (which

forms the floor of the pelvis) to become the anal canal. Just above the anal canal

the rectum will be dilated to form the rectal ampula . The rectum has three

transverse folds (figure 21); one right transverse fold and two left transverse

folds, these fold are made from mucosa, sub-mucosa and some smooth muscles.

Together these folds will form what we call the rectal valve.

Anal canal

Its length is about 4 cm, we will divide the anal canal into upper half and lower

half .

Left transverse

folds

right transverse

fold

Figure 21

23

# Upper half:

The epithelium that covers it is simple columnar epithelium like the rest of the

tract.

This epithelium comes from the endoderm.

It is supplied by the superior rectal artery which presents the terminal branch of

the inferior mesenteric artery.

It is drained by the superior rectal vein which drains to the portal vein and the

inferior mesenteric vein.(very important connection between the portal and the

systemic circulations)

When we look at the internal surface of the anal canal we can see longitudinal

folds, these called anal columns (figure 22). At the base of these columns we have

horizontal folds called anal valves, which connects the anal columns together.

Again anal valves are different from anal sphincters.

Sphincter smooth muscles.

Valve folds.

#Lower half

The epithelium that covers it is stratified squamous epithelium.

This epithelium comes from the ectoderm (like the skin and the epithelium of the

oral cavity).

It is supplied by the middle and the inferior rectal arteries which are branches of

the internal iliac artery.

Note: We know that the abdominal aorta will divide and give us right and left

common iliac artery, each one then will divide into internal and external iliac

arteries. The internal will go to the pelvis while the external will go to the lower

limb.

24

It is drained by the inferior rectal vein which opens into the internal pudendal

vein which drains into the internal iliac vein.

*There are no anal columns in the lower part.

Anal sphincters

# Internal anal sphincter

This sphincter is involuntary and formed from smooth muscles.

It is located at the junction between the rectum and the anal canal.

# External anal sphincter

This sphincter is voluntary and formed from skeletal muscles not smooth muscles.

It is found in three parts:

Deep part: very close to the junction between the rectum and the anal

canal (and thus close to the internal sphincter).

Superficial part.

Subcutaneous part.

Columnar folds

Figure 22

25

Reco-anal junction (figure 23 )

It is the junction that lies between the rectum and the anal canal. At this junction

we have:

Internal anal sphincter

The deep part of the external anal sphincter

Puborectal muscle : fibers of the levator ani muscle .

Now these three structure are called anorectal ring .

The end

Special thanks to :Safwan Abu rub , Ghassan Shbool,

Mohamad Widyan, Ahmad Kofahi, Alaa Hmaidat ,Ibrahim

Manasrah, Mohammad Jibril, Mohammad Refai.

Figure 23

19/59

8/12

15

Anatomy

Histology of the Accessory Organs of the GIT

Qasem Aldwere

Omar Shunnar

Monday, 31/10/2011 24/10/2011

Anatomy Lec. #8

Histology of the Accessory Organs of the GIT

*Please check the slides while studying this lecture, because there is information the doctor didn’t mention. Also, repeated information and unnecessary ones were removed from the lecture*

*The Lecture is very easy, and can be studied quickly. Enjoy while reading and studying it *

*The doctor started the lecture by answering few questions about the previous histology lecture, and all the information he said were mentioned in that lecture*

The lecture shows a guideline how to understand the topic, and how to digest it, and how to read it, not to go page by page and line by line from the textbook. I must give you a new method how to understand it.

The accessory organs start in the oral cavity with the Tongue, and then we go downwards to find the Pancreas and the Liver, these are the only accessory organs of the GIT.

The Tongue:

The dorsum of the tongue is divided into anterior 2/3 and posterior 1/3 by the Sulcus Terminalis, and it is covered by stratified squamous epithelia. The actual structure of the tongue is the epithelial layer, and a small thin but strong connective tissue beneath it, note that it is not loose connective tissue. Beneath them, the tongue is made of pure skeletal muscles, no fat tissue; it is one of the few organs in the body that doesn’t have fat tissues.

On the surface of the tongue, there are many types of the papillae: Filiform, Fungiform, Circumvalate, and Foliate Papilla. The Filiform Papilla is cord-like papilla, like the spines, pointed upward. They are the most numerous papillae in the tongue, and they are not taste buds. They

function in the cleaning of the oral cavity and the teeth. They are more functional in the animals, like cats. The other type is the Fungifrom Papillae, which appear like fungus. It has several folding and extensions, and they occur singly. They are richly vascularized, with lots of capillaries seen in them. The Circumvallate are the largest in size and least in number. They are surrounded by Trenches, and in these trenches at the lateral side they will have the taste buds. So the food will be trapped in these trenches, and the taste buds will secrete their secretions to function and taste the food. They also have some serous glands that help the taste buds in their function, and these are called Von Ebner Glands.

There are also other taste buds in the oral cavity, and these can be found on the palate, in the palatoglossal and palatopharyngeal folds. These glands will have around them some other cells, especially the supporting cells that keep them in their places. Also there are sensory cells to sense the presence in the food near the taste bud. You should also know that the buds on the anterior surface of the tongue taste the sweet food, the lateral surfaces taste the salty food, and the posterior surface taste the bitter food.

Let's move to the glandular part of our lecture and talk about the salivary glands in the oral cavity. We have Parotid, Sublingual, and Submandibular glands. The general architecture of these glands is that they are encapsulated, which mean there is a capsule made of connective tissue that surrounds the gland completely, this capsule sends some septae into the gland and divide it into lobes, and then there

are other invaginations and further septae that separate each lobe into lobules, and in the middle of these lobules we will have the functional part of the gland, which is the secretory part that lies in acini or tubularacini and the secretions of these glands will be powered into a central duct. Now the ducts will be named according to the structure around them: we have interlobular ducts, and interlobar ducts, and also we will have what we call striated ducts which are the unity of 2 intercalated ducts (the intercalated ducts are the ones that bring the secretions from the secretory part directly) together to form one duct which is lined by epithelia that have more mitochondria (The mitochondria will be used to generate energy to pump sodium and potassium mainly). This duct will convey the secretions to the interlobular duct, interlobar duct, and finally to the major duct.

Let's talk about the parotid glands in brief, because you have taken about it in anatomy. The parotid gland lies in front of the auricle, start upward from the temporomandibular joint and inferiorly it reaches the angle of the mandible and goes a little beneath that. There is a small clinical thing I want to talk about now: how can we differentiate between the infection of the parotid gland (like in mumps) and other infections in the same area that may look like the mumps? The solution here lies in the palpating of the angle of the mandible and seeing the

enlargement of the parotid gland, which should be firm enlargement that covers the angle completely that we cannot palpate it. The duct of the parotid gland comes medially from the gland and passes through the buccinator muscle (the cheek) and opens opposite to the upper second molar teeth.

The secretions of the glands can be: serous, or mucous. The serous secretions are watery secretions, while the mucous will be thick because it has polysaccharides. The glands are either serous or mixed, because we cannot find pure mucous glands; the parotid gland is from the serous part.

The thickness of the ducts differs from one type to another, but mainly they will increase in thickness with the increase of the secretions passing from there. So we will start with the intercalated ducts which have simple cuboidal epithelia, then when they connect in the striated duct it will have columnar epithelia, and then in the interlobular ducts they will be stratified cuboidal, then later they will turn into stratified columnar epithelia in the interlobar ducts.

How can we differentiate between the serous and mucous types of glands histologically? In the serous glands, the nucleus will be pushed on the periphery of the cell, while in the mucous ones it will be flat and adherent to the membrane. The second thing is the staining pattern, because when we use H&E staining, the serous glands will take basophilic dark stain, while the mucous ones will take fainter stain because they have polysaccharides which will be extracted during the preparation of the slide.

The sublingual glands will be under the tongue, and their ducts will pass from both sides of the tongue and in the floor of the mouth and open there. In some cases, there might be a clinical problem that might threaten the patient but it is not that much dangerous. Sometimes there is a calculus that blocks the ducts of these glands so there will be swelling in the ducts very fast, and the patient might think this is a very very fast growing tumor o.O, so we should locate the opening of the ducts and inject some saliva to remove the calculus. The sublingual gland is mainly mucous, and you can notice the faint staining of it.

Occasionally in the mixed-type glands, we will have a crescent-shaped serous part on the mucous glands, and we call this Serous Demilune. And also remember, that anywhere in the body where there are secretions, we will have Myoepithelial cells, because they aid in the process of the secretion.

The Pancreas:

The pancreas is described as a mixed gland, as it has both exocrine portion, and endocrine portion which constitutes only 1% of it. It secretes about 1.5 liter of juices every day into the pancreatic duct which secrete them into the duodenum. The pancreas has tubuloacinar cells, and has pyramidal-shaped cells that form the secretory acini. The bulk of the pancreatic secretions are bicarbonate and fluid secretions.

The pancreas has a capsule, that invaginates and sends septae to divide it into lobes and then lobules, and there are the endocrine portions of it scattered around the organ, and these portions are called islets of langerhans. The islets of langerhans are actually separated from the other portions through a continuous connective tissue capsule.

If we look at histological slides of the pancreas, we can easily differentiate the islets of langerhans and the capsule that surrounds them. If we look at an immunostain of it we can see the cells that produce the insulin too.

The Liver:

The liver is the largest organ in the body, and it has 2 lobes: the right and the left lobes. The right lobe has an inferior surface that can be palpated about one finger down of the costal margin. This surface marking is very important because if you want to do palpation and percussion to check for an enlargement of the liver, you should know where it is present exactly. [The doctor now started to talk about surface anatomy, and that it is the only part of anatomy that you should NOT forget in your whole life]

The liver also like pancreas has an outer capsule, that then sends septae and divide it into lobes and lobules. The liver also has macrophages that are called Kupffer Cells.

*The doctor now started talking about the Cardio-Vascular system and revising the types of the capillaries. I will just mention the important things that we should know about them in this system*

The capillaries that we have in the liver are from the discontinuous type. They will permit lots of exchange, and this is very important for us in the liver because it receives the food and fluids we eat and drink, and these are received through the portal system.

The liver constitutes of the hepatocytes that are present around the portal vein that brings the food from the portal system to the liver, where we will have most of the metabolism of that food. In slide 19 (up), you will find blue, red, and green circles, what are these? And how can we differentiate between them histologically?

The blue circle is the portal vein; the vein has a collapsing structure, and its main layer is the outer layer, the tunica externa. The red one is the artery, and the artery is smaller, its main layer is the tunica media where we have lots of smooth muscle, and it has circular outline. The green one is the bile duct, and it is simply just cuboidal epithelia.

Whatever is absorbed from the intestine, it will go to the liver and pass through a lobe of it by the portal artery. The capillaries there are discontinuous, so there will be free mixing between the portal and the hepatic contents, and then they will go to the portal vein after they were mixed and dealt with from the macrophages. The macrophages role here is important because the food comes from an external environment, and surely there are harmful materials in it. The portal veins then will collect in the central vein that will then go to the venous system and eventually to the right side of the heart.

The bile produced from the hepatocyte will have a different route: from the middle of the hepatocyte to the outer part of it, and then collects in the bile ducts that will lead it eventually to the gallbladder, and these ducts that convey the bile are called Canals of Hering.

The Biliary System:

Something to remember about this: the type of epithelia lining the gallbladder is tall columnar epithelia, and there will be microvilli for the absorption. We can differentiate it from other similar organs (like the intestines) by the absence of the mucous secretion cells which are present usually with tall columnar epithelia that has microvilli.

*Please refer to the slides, especially for the last subject*

Please forgive me for any mistake; I did my best in

writing and editing this lecture

Omar Shunnar

1

Anatomy

Development of the GI Tube

Mohammad Al-Haidari

Wesal Gharra

Tuesday, 1/11/2011

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9 / 12

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Anatomy- Lecture 9 Tuesday, 1/11/2011

Development of the GI tube

The GI tube, which is originally continues tube from the upper and most cephalic part to the lower and most caudal part, is made of specialized epithelium derived from endoderm and there is certain muscles and covering for this epithelium which are derived from mesoderm.

So there is a combination of 2 germ layers to form this highly specialized tube: Endoderm lining epithelium Mesoderm muscles and epithelium covering. The whole embryo develops from trilaminar embryonic disc; small, flat disc & made of three germ layers (ectoderm, mesoderm and endoderm).The ventral aspect of the embryo is continues with large cavity called the yolk sac. During formation of this important and highly specialized gut tube, part of the yolk sac will be incorporated, that means it will form part of the gut tube and the whole sac which was a large one will become smaller and smaller and constricted to a limited ventral connection which we call the vitelline duct which will be part of umbilical cord.

Vitelline duct

Classically we divide the GI tube into 3 segments: Foregut; the most cranial. Midgut; the one in the middle which is connected with previously the yolk

sac and then with the vitelline duct. Hindgut; the most caudal.

Gradually, the connection between the embryo and the yolk sac

becomes narrower, and a tubular vitelline duct is formed. Normally, the

vitelline duct disappears completely by the end of the embryonic period,

but an abnormal remnant may persist - for example: as a small

diverticulum attached to the small intestine (Meckel's diverticulum), or

a vitelline cyst or fistula.

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This picture shows a lot of v. important above mentioned and coming ideas… When we look at the adult alimentary tract we know that there are three arteries coming to these 3 segments:

Celiac tract for foregut. Superior mesenteric for midgut. Inferior mesenteric for hindgut.

Now what are the boundaries of each gut?! From the esophagus which is the most cranial part of the GI tube begins the foregut down to the 2nd part of duodenum where there is a special land mark directed to the left forming an entrance of the common biliary duct which makes a junction with the pancreatic duct, into the duodenum, this junction makes the land mark between foregut and midgut. In this picture, you can see clearly the junction between common biliary duct and pancreatic duct, that opens into the duodenum and forms the boundary between foregut and midgut.

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At this junction in the 2nd part of duodenum begins the midgut and extends to include: the rest of the duodenum, all the small intestine (jejunum and ileum), secum, appendix, ascending colon, hepatic flexure and about one third of transverse colon. This is the territory of the superior mesenteric artery and its branches: right colic, middle colic, ileocolic…etc In this picture appears the superior mesenteric A and its branches that supply the different parts of midgut. In the transverse colon, at about less than two thirds of it begins the hindgut down to the: splenic flexure, descending colon, sigmoid colon, rectum and upper anal canal. And of course this is the territory of the inferior mesenteric artery. Is the GI tube including the mouth? In the developing embryo there was a depression in the face between the brain and the pericardium called Stomodeum, it actually was between the brachial (pharyngeal) arches, the oral cavity belongs to this part, also this part includes a very important landmark called the buccopharyngeal membrane that will separate between cervical and cranial structures and the continuation of the esophagus which will descend to meet the connection with the stomach.

Look at this picture to see the

stomodeum (the primitive mouth).

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Wiki…

The tracheoesophageal tube will separate; part to the GI and part to the respiratory. In the cranial part of the gut tube, the whole tube is in connection with the respiratory organs of respiratory system. And at the caudal part there is another structure which actually will develop into adult structure that belongs to the urogenital system; allantois, cloaca and the urinary bladder. So cranially the whole foregut tube is connected to the respiratory structures and caudally the whole hindgut is associated with urogenital structures.

Look at this diagram and see: cloaca and allantois

As we said, very early in the embryonic life, the embryo (until the beginning of 4th

week) is actually formed of a simple oval disc before any folding into cylindrical

shape and before the closure of pores cranially and caudally. Later on the embryo

will start to fold upon itself, in the 4th or 5th week the embryo will appear as

C-shaped embryo, at this stage the cranial part will start to show the formation of

the branchial arches and dorsally we will start to see the bulges that are called

somites; actually they are collections of the paraxial mesoderm (closest part of

mesoderm towards the central axis- the notochord).

In this diagram you can see the C-shaped embryo, the branchial arches cranially and the somites dorsally.

buccopharyngeal membrane or oropharyngeal membrane, which forms a septum

between the primitive mouth and pharynx.

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Now let’s look at this cross section of the embryo…

Here, this is a very early primitive appearance of the whole embryonic Flat disc; there is ectoderm, mesoderm in between and endoderm lining over the yolk sac that is connected over the whole embryo at this stage This picture marks the beginning of folding of the embryo, we have a curvature cranially and a curvature caudally, the cranial curvature is going to enlarge and form most of the cranial part of the central nervous system. By this enlargement there is an invagination of the cranial part towards the ventral aspect of the embryo. This cranial part at the beginning it was the most cranial part of the developing embryo that means it was even cephalic to the developing brain, that part marks the heart, So the origin of the heart (the angioblastic cord) was cranial to the brain, later on within few days the invagination will bring the heart towards the ventral aspect and the color will be changed into red, the heart actually will take its ventral position due to this invagination. Look at the first picture in the 2nd page: see how the pericardial cavity was cranial and as a result of folding it became ventral. The whole embryo has curved upon itself; the cardiogenic area (heart tube area) invaginated to form a boundary. (I think the doctor meant this boundary will be with the foregut) If we look at the caudal part; it has another invagination, made of the whole curve of the tail fold; at this region there is another expansion in addition to the yolk sac, we called it the allantois that marks part of the future urinary organs. (In the first picture in page 2 you can see the allantois)

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So if we follow invaginations in both sides we can see that there is a connection with the respiratory cranially and with the urinary caudally. The yolk sac, its connection with the ventral aspect of the embryo was very wide and starts to constrict until it becomes a narrow ventral connection called the vitelline duct meaning that the foregut and hindgut are far away from the yolk sac now, only the midgut is connected with the yolk sac by this vitelline duct. By the 4th week (26 days) the whole tube appears as a tube connected:

Cranially associated with the heart tube In the middle connected with the vitelline duct which leads to the yolk sac Caudally connected with allantois

Relation of esophagus with trachea and: Esophagus and tracheal tube originate cranially from a single tube, and then partition in this tube will happen between them, the ventral aspect to the front will be the trachea (the respiratory part) as a diverticulum at the beginning and then it will divide to form the lung left and right buds, posteriorly or dorsally the tube will be separated to form the esophagus and very rapidly, the esophagus will elongate distally to join continuation of the gut tube (the stomach). One of the most common problems is when this connection doesn’t separate properly… (Due to a problem in the microphone, 2 min of the audio weren’t heard at all) If we look at the whole tube, there is a boundary between the gut tube and the region of the heart and pericardium, and distally is between the tail (allantois) and the hindgut. The region that separates the whole developing embryo urinary from the gut tube is called the cloacal membrane (arrow).

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And the region which separates the gut from the developing heart is a septum that we call it septum transversum ( ) The proximal part of foregut is separated from exterior by buccopharyngeal membrane that marks the area of stomodeum (the oral cavity). So the gut is connected to two membranes (buccopharyngeal & cloacal), both of them are to the exterior, and both originate from the ectoderm in the oral cavity and in the anal region. That marks the 2 junctions of this gut tube between the mucosa of the tube and the actual skin. The two extremes of the tube; upper extreme1 (oral cavity, pharynx and upper esophagus) that is very close to the stomodeum and related structures, and the lower extreme2, their covering epithelium is of a different type, not absorptive type; it’s stratified squamous. In addition these two connections are connected to the ectodermal part and part of the skeletal elements that’s why these extremes in addition to the different epithelium will have a different musculature (collection of muscles). If we examine the tube in adults; it’s a very long tube; proximally we have the foregut, below the septum transversum (below the diaphragm) we can examine the stomach, duodenum, very long small intestine, very large intestine until it reaches the terminal rectum and anal canal. What happens during development that this tube becomes very long?! At the beginning the tube length is the same as the embryo length, as a result of modifications this tube later on becomes very long. The stomach is the most dilated part of the tube, other dilated parts are the secum and the large intestine, the rest of the intestine is still narrow tube although it’s long. What happens to the stomach is a rotation, actually a clock wise rotation if we look from above and rotated 90˚, in addition to rotation bulging or dilatation will occur,

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this will create the shape of adult stomach. The stomach is innervated by the vagus nerve, when the vagus descends into the body, it’s bilateral of course because it is cranial nerve, thus we have left and right vagus, it goes along the gut tube; one on the left and one on the right. We have anterior and posterior nerves of the stomach, not left and right because of the 90˚ rotation. If we look at the gut tube in the region of the stomach, dorsally there is a continues vessel running along the whole length of the visceral part of the developing embryo, we call it the dorsal aorta. Dorsal aorta Wiki… During the formation of the 3 parts of the gut tube, they take their arteries from the dorsal aorta, we mentioned them before: celiac, superior and inferior mesenteric arteries respectively supply the foregut, midgut and hindgut. These arteries reach to the tube through membrane; the tube is connected dorsally (posteriorly) to the dorsal aorta by double layered dorsal mesentery. To the front the tube is connected to the body wall through ventral mesentery. Ventral mesentery must reach an area where vitelline duct and the connection of the yolk sac, continues with the body so there will be no wall for the mesentery, that means the ventral mesentery isn’t continues like the dorsal, it will interrupted in the region of the yolk sac and the vitelline duct. In adults when we examine ligaments in the region of the liver or the stomach, we can see that there is a free border ligament connected from the umbilicus to the visceral surface of the liver; this is called the falciform ligament, it has a free end of round ligament called ligament teres, this is actually the end of ventral mesentery.

Each primitive aorta receives anteriorly a vein—the vitelline vein—from the yolk-sac, and is prolonged backward on the lateral aspect of the notochord under the name of the dorsal aorta. The dorsal aorta gives branches to the yolk-sac, and is continued backward through the body-stalk as the umbilical arteries to the villi of the chorion. The two dorsal aorta combine to become the descending aorta in later development.

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So now we can define: Ventral mesentery: double layer peritoneal connection of the gut tube to

the wall. Dorsal mesentery: double layer connection of the gut tube to the dorsal

aorta and the posterior body wall and through dorsal mesentery vessels approach and reach the gut tube.

In adults mesentery of small intestine is very short (about 6 inches) from duodenojejunal junction in the left down to the right iliac fossa. But the whole tube is about 20 feet. The vessels when approaching this tube will continue branching and branching until making a sort of network so that even convolusion will not obstruct the blood supply, that’s why this tube will perform a special method by which elongation and repeated branching of the vessels take place and this is what we call herniation; the whole tube will leave the body through the umbilical cord for a certain time, about week 5 and will remain outside the body to continue elongation and branching of the vessels and then it will return back in at week 10 or 11. Human embryo in the 7th week showing the physiological umbilical herniation of the midgut into the extra-embryonic coelom (chorionic cavity remnant) within the developing umbilical cord. (Wiki)

Rotation and modification of the stomach and the small intestine are the most important things; we will discuss them in the next lecture after the holiday Insha’Allah…

That was all! I added some pictures to clarify ideas, and also u can go over the slides of the doctor to

make things more understood.

أضحى مبارك... كل عام وأنتم إلى اهلل أقرب

26/59

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25

Anatomy

Blood Supply of GIT & Portal Circulation

Saleh Bani-Hani

Audai ma'aiah

Wednesday, 2/11/2011

24/10/2011

Page 1 of 15

In this lecture ,we will take about the liver .gallbladder , pancreas ,some surface anatomy

and important landmarks of the abdomen ,and finally the blood supply of the GI tract &

portal circulation.

Liver

as you know the liver is located within the right hypochondriac region and also in the

epigastric region .it's very important organ and it has several functions, but according to the

digestive function ,it produce the bile which stored in the gallbladder. (follow the figures on

the next page)so the liver produce the bile ,the bile will be stored within the gallbladder until

we need it when we eat fat because bile is important in the digestion of fat .now as we know

,the bile carried by the left and right hepatic ducts which joined each other to form the

common hepatic duct .the common hepatic duct will join with the cystic duct and its name

become bile duct .the bile duct behind the 1st part of the duodenum will join the pancreatic

duct .now the result is what we called the hepatopancreatic ampulla or ampulla of vater

which opened into the 2nd part of the duodenum and this opening makes a fold of the

mucous membrane which is called major duodenal papilla .of course we have a sphincter

around the hepatopancreatic duct or ampulla and this sphincter is called sphincter of oddi.(

The doctor said that in the book, they mentioned the most main things or structures ,but we

almost have variation for everything in our body), one of these variation for example:- the

pancreatic duct and the common bile duct which may open in to the duodenum in separate

,in its not necessarily that the pancreatic duct must join the bile duct,e3ni to each other

some people these two ducts open in separate location into the 2nd part of the duodenum.

Page 2 of 15

In order to identified the different parts of the liver and understand their location, we must

look at the two surfaces of the live ,the 1st one is called the superior anterior surface and

the 2nd one is called the posterior inferior surfaces or visceral surface because its mainly

related to the viscera .

now when we look at the superior anterior surface ,we can see here the left and right lobes

,also we can see the falciform ligament which is fold of the peritoneum .at the root of the

falciform ligament ,we have another ligament which is called ligamentum teres or the

round ligament of the liver .the falciform ligament and most of the ligament of the liver are

fold of the peritoneum ,but when we come in to the round ligament or ligamentum teres

which remaining part of the umbilical vein he represent t peritoneum, this,its not related to

carry oxygenated blood to the embryo .as you know that after delivery ,there is no need for

the umbilical vein and its obliterated and replaced by fibrous tissue .in the anterior view, we

can see only the fundus of the gallbladder which is related to the posterior inferior surface

of the liver. Now in order to see the other parts of the liver and the organs which are related

to the liver, we should look at the posterior inferior surface .we see the inferior vena cava

Anterior view Posterior view

Page 3 of 15

IVC ,and to the left of the IVC we have what we called caudate lobe, and to the left of the

gallbladder here we have the quadrate lobe ,so anatomically we divide the liver into four

lobes ,(left, right caudate and quadrate lobe). As you can see on the posterior inferior

surface, we have the IVC, gallbladder and the left lobe is related to the stomach ,so this part

which is related to the stomach is called (Gastric impression) and here we have small

depression which is made by the esophagus (Esophageal impression) .the quadrate lobe

related to the duodenum .now ,at the right side of the gallbladder we have colon (colic

impression), then we have the right kidney (renal impression) and the right suprarenal

gland( suprarenal impression) .the anterior relation to the liver is the right and left costal

(costal margin is formed by the costal cartilages page" stthe figure in the 1 look atmargins "

of the ribs number 7,8,9,and 10 ).so the liver because its located in the right hypochondriac

region and the epigastric ,its related to the right and left costal margins ,also its related to

the diaphragm which separate the liver from the bases of the pleura of the two lungs .

The gallbladder is related to the visceral surface of the liver and when we look at the

anterior surface of the liver, we can see only the fundus .the fundus of the gallbladder is

.ninenumber behind the tip of the right costal cartilage of the rib located immediately

Anatomically ,its related anteriorly to the liver and backward related to the duodenum .

Pancreas

As you know that the pancreas is formed of head, body and tail .the head is embedded

within the C-shape of the duodenum .the body run behind the stomach (its more accurate to

say behind the lesser sac which is behind the stomach). The pancreas is retroperitoneal

organ .the tail reaches the spleen .along the superior border of the pancreas we have this

very important artery which is the splenic artery (look at the figure page #8) so when we

come to the relations of the pancreas ,anteriorly we have the stomach ,lesser sac, part of

transverse colon and part of the transverse mesocolon (mesentery of the transverse colon).

Posteriorly the pancreas cross the IVC and aorta,also behind the pancreas we have the

splenic vein which joined the superior mesenteric vein to form the portal vein just behind

the neck of the pancreas(look at the figure page #11).

Note: according to the nerve

supply and lymphatic drainage,

there is a lecture for this topic.

Page 4 of 15

Surface anatomy

Previously ,we described the two vertical lines and the two horizontal lines .the vertical lines

pass through the midpoint of the clavicle ,that’s why we call it the midclavicular line and

also pass through the mid point between the superior anterior iliac spine and the symphysis

sub the ,we have s.the transverse or the horizontal line page) st(see the figure in the 1pubic

costal line and the intertubercular line .sub costal passes through the lowest point of the

lowest point of the costal margin is made by the you that remainedwant to Icostal margin .

line pass through the costal cartilage number sub costal,so the number 10costal cartilage

10 on the both sides .the intertubercular or the transtubercular pass through the iliac

tubercle (we have the iliac crest and if we follow the iliac crest, we will find a small elevation

which is the iliac tubercle) and the line which pass through the iliac tubercle in both sides is

called inter or trans tubercular line .sub costal line located at the level of L3 while the inter

or trans tubercular line located at level of L5 .

We have other two horizontal lines which are important in the surface anatomy. one is

called transpyloric line(page #5). Remember the linea semilunaris (which lines the lateral

border of rectus abdominas muscle).this line upward will pass through the tip of costal

cartilage number nine which is the location of the fundus of gallbladder (at the right side).so

both sides pass through the tip of costal cartilage number nine in the transpyloric line will

.in fact pass through the pylorus of the stomach.we called this line trans pyloric because it

there are many other structures which are located at the level of this line ,this include the

duodenum, transverse colon,duodenojejunal junction ,the hilus of the two kidneys and the

fundus of the gallbladder.

As a summary , the sub costal line pass through the tips of costal cartilage # 10 and located

at the level of L3.from its name ;sub costal means below the costal margin ,and the lower

point of the costal margin is at the tip of rib #10. But the transpyloric line will pass through

the tips of costal cartilage # 9 of both sides .

Sub costal line:- L3

Intertubercular line:-L5

Question:

which line is used to

divide the abdominal

wall into 9 regions ,sub

costal or transpyloric?

Answer :sub costal

Page 5 of 15

So in order to divide the abdominal wall into 9 regions ,we have two horizontal lines and two

vertical lines .the two horizontal line are the sub costal and the inter or trans tubercular line.

*In addition to these two lines, we have other horizontal line which is called the transpyloric

line.

We have other horizontal line which is called the inter cristal line(supracristal line) which

pass through the right and left iliac crest .this is located at the level of L4 .its important in the

lumber puncture(in the case of meningitis ,the only way to diagnose meningitis is to take

sample from CSF ),the surface line to introduce the needle is either between L3-L4 or

between L4-L5.e3nii either above L4 OR below L4 to inter into the subarachnoid space in

which the CSF in located .so it's important to know how to determine the L4.we put the

finger on the iliac crest, then we moved the finger to the midline so the finger will be on the

L4 ,then we introduce the needle either below or above L4.this process is called lumber

puncture .

There is other land marks which you can find it in snell page 764 because there is no enough

timeby the doctor to discuss them .

The blood supply of the GI system

Note: after you finish the blood supply, there is a summery for all the branches

that we are going to discuss now so you can follow the map while you are reading

the discussion. Look at the page #10.

The digestive tract and the associated organs in our abdomen has supply by three arteries.

In embryology, you know that the digestive tract form of foregut ,midget and hindgut. And

Page 6 of 15

the structures which are developed from the foregut are supplied by what we called celiac

artery ,while the structures of the midget are supplied by superior mesenteric artery, while

the structures of the hind gut are supplied by inferior mesenteric artery.

our digestive system is supplied by three arteries and all of them are branches of the

abdominal aorta. Now just below the diaphragm at the level of T12 ,the abdominal aorta

gives celiac artery and just below the celiac we have the origin of superior mesenteric artery

and downward we have the inferior mesenteric artery .these three arteries supply stomach,

liver ,pancreas, small intestine and large intestine until the middle of anal canal(the upper

half and lower half differ in each other in term of epithelium ,arteries ,veins and embryonic

origin. LOOK at this table:

Lower half Upper half

Stratified squamous Simple columnar epithelium ectoderm endoderm Embryonic origin

Middle & inferior rectal arteries

Superior rectal artery Blood supply

Inferior rectal vein which is connected to the systemic circulation

Superior rectal vein which is connected to the portal circulation

Venous drainage

The middle of the anal canal represent one of the most important sites for anastomosis

between the portal venous system and the systematic venous system which will describe it

in the next lecture.

Page 7 of 15

of the abdominal aorta just below the aortic hiatus in the branch firstNow we come to the

diaphragm ,we have this large but very short artery which is the celiac trunk or celiac artery.

This celiac artery give us three main branches. The first one is called left gastric artery which

turn to the left and run upward to supply the right half or the right side of the stomach ,it

runs along the lesser curvature of the stomach, it supply not only the stomach but also the

lower part of the esophagus (look at the esophageal branch which pass through the

esophageal hiatus of the diaphragm and ascend to supply the lower part of the esophagus.

turn to the left behind the stomach and this is called trunk celiacof the branch second The

the splenic artery (we said when we discuss the pancreas that the splenic artery runs along

the upper border of the pancreas behind the stomach ).the splenic artery will reach the

short gastricis the st1termination, it will give us two main branches ,the beforespleen and

that will make anastomosis with the branches of the left gastric to supply the fundus and the

the left s branch of the splenic artery give nd2upper part of the body of the stomach .the

gastroepiploic artery (left gastro-omental artery) which runs along the greater curvature of

the stomach. The third branch of the celiac trunk is the hepatic artery. The common hepatic

artery will give gastroduodenal artery and then its name become hepatic proper(in snell

the hepatic artery gives the gastro duodenal and the hepatic artery ).the gastro duodenal

onedivide into two branches , npart of the duodenum the startery descend behind the 1

supply the upper half of the pancreas and the upper part of the duodenum and that’s why

we call it the superior pancreaticoduodenal artery ,second terminal branch of the gastro

duodenal artery is called the right gastroepiploic artery(right gastro-omental artery)which

turn to the left along the greater curvature to meet and make anastomoses with the left

gastro epiploic artery(right gastro-omental artery). Now as we know that the hepatic artery

proper will go to the liver ,it will run within the lesser omentum which connect the stomach

with the liver then divided into right and left hepatic arteries proper which supply the liver

with nutrition and with oxygen ( because the liver receive another blood vessel from the

portal venous system .so, the celiac artery will supply:- (lower part of

duodenum,stomach,upper part of duodenum, upper part of pancreas ,liver and spleen.

Page 8 of 15

which arise just superior mesenteric artery dominal aorta is the of the ab second branchThe

below the celiac artery , and supply the lower part of the duodenum, lower part of the

pancreas, jejunum ,ileum ,cecum,appendix ,ascending colon and the right 2/3 of the

transverse colon. It will give several branches:-

which supply the lower part of the artery pancreatic duodenalthe inferior ,it gives st1

pancreas and the lower part of the duodenum ,so the panaceas and the duodenum are

branch is ndmesenteric artery .the 2 rsuperiosupplied by branches from both the celiac and

called the middle colic artery which ascend upward and it divide into right branch and left

into ascending branch and which divide artery right colicbranch is the rdbranch. The 3

descending branch. The 4th branch is the ileocolic artery which is divided into anterior cecal

and posterior cecal which supply part of the ileum , cecum and ascending colon .the

posterior cecal artery will give the the appendicular artery so the artery which supply the

appendix comes from the posterior cecal artery which is branch of the ileocolic artery .the

final branch is the jejunum and ileal arteries which gives about 12-15 small arteries which

supply the jejunum and ileum .

Page 9 of 15

these two figures shows the ileal and jejunal arteries which gives many side branches which

anastomosis with each other ,and these called arterial arcades in jejunum and ileum .

Now the third branch of the abdominal aorta is the inferior mesectric artery which supply

the rest of the digestive system which is : left 1/3 of the transverse colon, descending

colon,sigmoid colon ,rectum and the upper half of the anal canal . the terminal branch of the

inferior mesenteric is the superior rectal artery which make anastomosis with the middle

and inferior rectal artery .the inferior mesenteric artery will gives :1st left colic artery which

gives two branches , ascending and descending branches which supply the left 1/3 of the

transverse colon and the descending colon. 2nd branch is the sigmoid arteries which supply

the sigmoid colon , and as we said the terminal branch is the superior rectal artery .

Page 10 of 15

abdominal aorta

celiac artery

left gastric artery

splenic artery

short gastric arteries(6)

splenic arteries(6)

left gastroepiploic artery

hepatic artery

cystic artery

right gastreic artery

gastroduodenal artery

right gastroepiploic artery

superior pancreaticoduodenal

artery

right hepatic artery

left hepatic artey

superior mesentric artery

jejunal and ileal arteries

inferior pancreaticoduodenal

artery

middle colic artery

right colic artery

iliocolic aretry

anterior ceal artery

posterior cecal artery appendicular artery

ileal artery

colic artery

inferior mesentric artery

left colic artery

sigmoid arteries(2 or 3)

superior rectal aretries

Summary of the branches of the abdominal aorta that supply

the GI tract

Page 11 of 15

The portal circulation

As we know ,we divide the veins into either systemic venous system or portal venous

system .by portal venous system , we means the veins that carry the digestive food to the

fat which is exceptliver . as we know that these veins will carry all types of digestive food

absorbed by the lymphatic nervous system (in histology , the villi of the small intestine have

lacteal which is lymphatic capillary –junqueira page 270 ) . these lacteal( lymphatic capillary)

absorb the digestive fat and carry this fat into the blood without passing through the liver

,otherwise all the digestive food including vitamins and others will absorb by what we call

the portal venous system and carried to the liver .

The portal venous system composed of following veins:-

The first one is the splenic vein which again start from the spleen ,run to the right behind

the pancreas .this vein will join to the inferior mesenteric vein which receive blood

from the terminal part of the digestive tract ( from the same structures that is

supplied by the inferior mesenteric artery).now when the splenic vein joins the

inferior mesenteric vein, the resulted vein also called splenic vein (splenic vein +

inferior mesenteric vein = splenic vein) (its name remain splenic vein), now the

splenic vein just behind the head of the pancreas will join the superior mesenteric

vein which drains the same structures which are supplied by the superior

mesenteric artery , and in this point the portal vein is formed (splenic vein+

superior mesenteric vein = portal vein). Before the entering of the portal vein to the

liver , it will receive the left gastric vein which drains the right side of the stomach

(lesser curvature) and the lower part of the esophagus . within the lower third of the

esophagus , the branches of the left gastric vein make anastomosis with the

esophageal vein which drains upward into the azygos vein which is a systemic vein

which goes to the superior vena cava which receive the blood from the upper part of

Page 12 of 15

the body above the diaphragm (so this is another location for anastomosis between

portal venous system and the systemic venous system .

Note:

SVC: drains the blood from parts above the diaphragm

IVC: drains the blood from parts below the diaphragm

azygous vein: drains the thoracic wall, and the thoracic wall located above the

diaphragm so the azygous will drains in to the SVC.

The portal vein carry the venous supply and digestive food from the digestive system to the

is the arterial blood which is st1two types of blood , receiveliver ,so the liver will

that provide the liver with oxygen and nutrition ,and hepatic arterybranch of the

food and the venous blood from the digestive carrywhich the portal veinis nd2the

digestive tract .these two types of blood will mix within the sinusoid of the liver and

after exposure to the hepatocytes , the venous supply from the liver will be carried

by the hepatic vein which carry the venous drainage from the liver and binds to the

inferior vena cava just behind the liver .the hepatic vein is not part of the portal

venous system (portal venous system consist of these veins that carry digestive food

and venous supply from the digestive tract to the liver) . but the vein which collect

Page 13 of 15

the venous blood from the liver to the inferior vena cava in not part of the portal

. be careful to this pointvenous system. Its part of the systemic venous system .

was in the middle of anal canal (between the superior rectal vein which s ianastomos st1

belong to the portal venous system and the middle & inferior rectal vein which

important to location. Its nd2belong to the systemic venous system ) ,and this is the

remember the sites of anastomosis between portal venous system and systemic

s between portal venous system isite for anastomos rd3we have system. Nowvenous

and the systematic venous system .its location in the umbilical region. As we know

we have the paraumbilical vein which connect the veins around the umbilicus to the

portal venous system , and we have systemic veins also . and finally we have

anastomosis between the colic vein which are portal and we have also systemic vein

around the ascending and descending colon.

the numbers on the figure represents the locations of anastomosis :1,2,

1

س

2

3

Page 14 of 15

Why these anastomosis are important ??

Because in case of the portal hypertension ( in case of liver cirrhosis that create portal

hypertension) this will create back pressure within the portal venous system .this

back pressure will lead to dilatation of the veins at these locations of anastomosis

which lead to many diseases ( in case of the dilatation of the veins in the anal canal,

this will lead to hemorrhoid which will cause pain and bleeding).now if the bleeding

covers the stool, this is hemorrhoid ,but if the blood mixed with the stool, this may

cause by other causes such as bleeding peptic ulcer or cancer in the digestive tract.

Also the portal hypertension will lead to dilatation of the veins in the lower 1/3 of

the esophagus and this is called esophageal varicosis and this also will cause

bleeding and the patient will have vomiting blood ( hematemesis) . also the para

umbilical veins may becomes diluted which appears as radiating veins in all

directions in the umbilical region and this also indicate portal hypertension .

Done by

Audai ma'aiah

بخير.............اضحى مبارك 9002 و دفعةكل عام

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Anatomy

Development of the GIT 2

Mohammad haidari

Amen al-beek

Monday, 14-11-2011

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بسم هللا الرحمن الرحيم

المون في ضلل فأروني ماذا خلق الهذين من دونه بل الظه مبين()هذا خلق هللاه

~11~لقمان

Last time we reviewed the alimentary canal or the digestive tube and we divided the tube

into three regions; foregut, midgut and hindgut.

We reached the step where the stomach which is the most dilated part, and we know its

actual position and size in the adult, but how it’s formed? It is formed from the same single

tube, we also know that this part of the alimentary tract is connected both to the front of the

body (anterior-abdominal wall) and to the back of the body (posterior abdominal wall) by

double layer mesenteries called ventral and dorsal mesenteries.

Because they are in the region of the stomach, we call the ventral mesentery >

ventromesogastrium and the dorsal one > dorsomesogastrium.

Now, below the foregut, there is no ventral mesentery, so in the midgut where the small

intestine is going to start (which is a very long convoluted tube), there is no ventral

mesentery, we see that it’s (midgut) connected toward the center of the embryo (to the yolk

sac or the umbilical cord) by the vitelline duct, so there is no ventral mesentery in midgut,

only dorsal mesentery.

Dorsal mesentery of midgut is going to traverse because this mesentery is the site which the

blood vessels should come and divide to all organs. So dorsal mesentery of midgut is the site

where superior mesenteric artery is passing between the two layers.

So, we see that there are many convolutions and elongations which will happen in the

intestine but remember there is no ventral mesentery.

Dorsal mesentery in the adult will be the root of mesentery for the small intestine, it’s

actually the right root of mesentery.

So the right root of the mesentery of the small intestine come from dorsal mesentery

because there is no ventral.

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** Starting again from the stomach, you can see

in the picture both mesenteries, the dorsal & the

ventral one. that means mesogastrium ventral

and dorsal.

With the modification of the stomach which we

know, the stomach of the adult is dilated part

mainly to the left side and more or less in a

horizontal position, so this original tube is going

to turn upon itself, these two nerves originally

right and left –vagus– will turn to be anterior

and posterior, so that a clockwise

rotation by 900 will result in the

twisting of this tube but this is

longitudinal twist.

Now if we talk a look or if we look

to it from different angel there is

another twist which is going to

happen in between cranio-caudal

part of the organ, so there is there

is a twist from the cranial part (in

the junction with esophagus) and

the caudal part (is the pylori: the

beginning of entrance of

duodenum), with this another twist there is another twist which is about more or less in the

horizontal position.

Another twist which will bring the superior or cranial part or the cardiac junction downward

and to the left. And the pyloric or distal or caudal part will be brought upward and to the

right, they were originally cranio-caudal in the adult more or less a proximate each other.

So the shift or the dilatation or the twist of stomach will take place in two directions: the first

one is vertical which will bring the dilatation to the left side and the other one is a vertical one

which bring down the cardiac junction and lift up the pyloric junction of the stomach.

This how the original sac of the stomach is formed, in addition to the twisting, there is a more

rapid dilatation and bulging of the left side, so there is the left side with the rotation and

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dilatation is going to take place. here it is going to take with it the

dorsal mesentery, and because of this larger dilatation, the dorsal mesentery will be pulled

with umbilical cord زي ستارة >> this how greater momentum is going to be formed because

it’s attached to the greater curvature & because of the greatest dilated part.

so the dorsal mesentery will be responsible for the formation of greater omentum which is

attached to the left part of the stomach.

On the right side, the ventral mesentery is terminate at the level of the umbilicus to the

anterior abdominal wall, the rotation is still limited to this part of the stomach, so the adult

shape of the stomach will be more or less like this; a cardiac end which is shifted slightly to

the left and going down and pyloric end is shifted to the right and upward and the whole sac

is dilated largely to the left side, connected to the dorsal-mesogastrium in the fully developed

stomach & this is going to be greater momentum .

Summary of stomach developmnet steps:-

1- Lesser curvature is directed to the right, while greater curvature is directed to left.

2- Left surface is directed anteriorly, right surface is directed posteriorly.

3- Formation of a peritoneal sac behind the stomach, called lesser sac.

4- Left & right vagi will be anterior and posterior gastric nerves.

5- Ventral mesogastrium forms lesser momentum, capsule around liver, falciform ligament

and coronary ligaments

6- Dorsal mesogastrium forms gastrosplenic, lienorenal ligaments and greater

momentum .

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Now, What will happen inside mesentery itself??

And we suppose that this a

septum which separate the

abdominal region from the

thoracic region, this is what we

call it Septum transversum and

this will be going to be a

diaphragm .

Within the ventral mesentery the

Hepatic diverticulum, which is the

origin of the liver, will start, it

begins as very small cord

appearing in the front -anterior- of the stomach, within the two layers of ventral mesentery

to the front of the abdominal wall, this organ is going to enlarge rapidly to form the liver, so

it actually push the two layers of ventral mesentery.

>> if there is no barrier above to it then it will continue into the thoracic cavity, but there is a

barrier which is the septum transversum.

Actually when we examine the liver in the adult we see that the liver is in contact with the

diaphragm without a membrane that means that the bulge of the liver when it increased it

separates the 2 ventral layers and become in the contact with the diaphragm in area we call it

bare area of the liver.

Inferiorly this is enlargment in the ventral mesogastrium, so its limited by border of ventral

mesentery, & there is no place to go downward, so the limit of the enlarging liver inferiorly is

limited by free border and from this organ to the front of the body, there is ligament called

falciform ligament .

As a summary :-

The liver is limited superiorly by Septum transversum, inferiorly by free border of ventral

mesentery and connected to the stomach (lesser curvature side) by falciform ligament

which is part of venteral mesentery .

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This is part of ventral mesentery is house another important organ which also inferiorly to

other organs related to the main foregut tube; the gall bladder; cystic duct will be formed

again inferior to the liver.

But there is another important organ going to be formed in the inferior region also which is

the pancreas.

The pancreas develops from two:

1. The ventral pancreatic bud.

2. The dorsal pancreatic bud.

And both of them are going to be pushed toward the posterior abdominal wall, so they won’t

stay within the membranes of the mesogastrium, finally they are going to be

retroperitoneum.

How this is form ??

1. here is the region of the liver And Gallbladder within

the ventral mesentery .

1. Below of them the ventral bud of pancreas.

2. And the dorsally we have stomach and most

posterior one is the dorsal bud of pancreas.

And these buds of the pancreas are going to be pushed

behind the mesentery so that will be fixed to posterior

abdominal wall “retroperitoneal “.

In adult pancreas, we have head, neck and elongated part (body), in the region of the head

actually there is a bulge and two ducts; a main a pancreatic duct and minor pancreatic duct,

so the region of the head is made of two parts or two original buds.

Now, the second part of the caudal part of foregut (duodenum) is going to twist following

the rotation of the stomach and by this rotation is going to push the ventral pancreatic bud

posteriorly.

so when the duodenum takes its position “C-shape in the adult and concave to the left”, the

ventral bud of pancreas will be pushed dorsally but both of them ”two pancreatic buds” will

be trapped within the C-shape duodenum, so these two buds will fuse together, and the

adult pancreas will be shown in one side .

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>>both pancreas and duodenum will be behind the peritoneum.

Q: why the liver will stay in their position when the duodenum twists??

A:The ventral bud will be pushed dorsally, so it’s actually outside ventral mesogastrium so it’s

nothing to do with the liver, the duct will come with it but the liver as organ will not share in

this rotation of the duodenum.

Distal to the duodenum, there is the continuation of midgut, here there is slight complexity

of information of this very long tortuous tube which we call later on small intestine, because

these modifications take place usually within few weeks; week five and still by the end of

week ten or beginning of 12th week, when these modification should end, and after that

when we examine a fetus in this age we expect to find an adult elementary tract.

The tube below or caudal to the duodenum is the midgut, remember that the midgut begins

at the end of the second part of duodenum as discussed in the last time.

The adult small intestine is a very long tube, & in the embryo, there is no ventral mesentery, it

will elongate & convolute on itself and become very long convoluted tube.

At the same time when the liver is enlarged, because this enlarging organ will take all the

space in the cavity in the embryo and there is only one connection with the outside that is

umbilical cord, so, the intestine will have no place to elongate and has the modification

except leaving the abdomen, so actually will leave the abdomen and it will appear if u

examine a sonogram of this age, the umbilical cord bulge between week five and week ten or

week eleven, this bulging because of herniation of the small intestine or midgut into the

umbilical cord, because there is no space for elongation.

Classically this turns is long turns is usually 2700 degrees and the direction is opposite to the

stomach “stomach is clockwise direction” but here is anti-clockwise direction.

Now let’s follow step by step:-

• Midgut loop rotates 90° anticlockwise around the axis of superior mesenteric artery.

• At the 10th week, intestine returns back to the abdomen posterior to superior

mesenteric artery occupying the central part of the abdomen.

• Large intestine undergoes another 180° anti-clockwise and occupies the right side of

the abdomen.

• The net of rotation equal 270°.

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** The advantages of this complex rotation are to ensure elongation and approaching

blood vessels will not be obstructed.

So there will be a repetition of division of the vessels approaching this tube “the origin

blood supply by superior mesenteric artery” but it can’t reach it as a simple tube or one

artery so it divide and anastomose and that is why we have intestinal arches of the vessels,

these arches take place during this period of rotation and physiological herniation.

dorsal part

Ventral mesentery

8 | P a g e

You must ensure that the long tube of small intestine in the center of the abdomen and the

rest of the midgut which should be part of large intestine and cecum will take another

position, the twisting here of the whole the tube and should be located in one position but

the twisting is not the same in all the tube.

how??

Classically, we consider the straight tube leaving attachment to the vitelline duct and return,

it divide into two loops, if u look from front, there is one upper and one lower, classically we

call it a cranial tube or loop and the caudal tube, & what limits cranial and caudal is the

connection with vitelline duct.

both of them will rotate 900 when they leave their domain only the cranial will rotate 1800

when they return, the cranial is the side where the small intestine is formed & the caudal is

the side where the cecum, appendix, ascending colon, hepatic flexure and about half of the

transverse colon will form, so the caudal part of this U-shape tube will not rotate as much as

cranial part and for that, when it return the caudal part, it will take the position which we

know in the adult “the cecum, should be in the right side”.

At the beginning, it was high “sub-hepatic” and it should descend to form descending colon,

hepatic flexure and part of the transverse colon.

The remaining part of the midgut is actually the very long tube which twisted to 2700 and by

this twisting, it will return and pulled toward the root of mesentery.

We know when we examine the adult we know that the root of mesentery is an oblique line

and posteriorly crossing the aorta and posterior abdominal wall where the superior

mesenteric artery enters.

As a summary; 2700 is divided as following:-

900during herniation.

1800during retraction

The only part u can see from the largest part of the midgut which still connected to the

dorsal mesogastrium is small intestine, so it will be pulled toward the center.

While talking about this subject, we need to understand few terms, there is a term called

intraperitoneal & there is one we call it retroperitoneal. You see the liver is intraperitoneal

except for area where it pushes the membranes away (bare area).

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If the whole viscous is covered; this is the intraperitoneal. & when it pushed toward the

posterior abdominal wall without covering (only the anterior surface is covered) this is the

retroperitoneal.

Classically we know that in the adult that anything is intraperitoneal is movable. & anything

retroperitoneal is fixed; we can’t move it.

If you have a mass in the abdomen, e.g., a tumor, and then you want to decide whether this is

in the large intestine or is in the small intestine, So if it’s fixed; then it must be either

ascending or descending colon, & if it is movable then it should be either a small intestine or a

transverse colon because this also covered by the greater momentum so it’s movable.

But to differentiate, you should know the oblique line of the route of mesentery. When you

move the mass, if it move up or down; you will see this is not a small intestine because small

intestine is moving obliquely.

So it moves obliquely with the route of mesentery which running obliquely from

dudenojejunal junction to the ileocecal junction. This is a very common test you use it in

medicine.

Finally, remember we forward the tube from stomodeum and from the pharyngeal

membrane and from the septum transversum., but if you remember in the caudal end there

is another junction through the allantois, will be the end of alimentary tract, and that what

we call it the Hindgut.

Here again, separation (at the beginning) is a common area which we call it cloaca Again a

connective like the stomodeum to the exterior by the ectoderm.

This going to be separated gradually, actually by two folds; one superior fold and one inferior

fold, when they approach each other a separation between the two tracts of the two

systems will take place, this is normally.

And we know that when we study the adult perineal region we know that there are two

triangles, one of them is urogenital (ventral) the other one is the anal triangle (dorsum), this

actually marked the end of these two systems as you can see urinary bladder is again

endodermal it was originate from the same terminal part of this gut tube from the hindgut.

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The slides contain large numbers of abnormalities which occur during development some of

them are common which we should concentrate on but one of the problems that happens in

the hindgut is the imperforate anus where the ectodermal gate will not open.

One of other abnormality which in your book they concentrate on is where the anterior

abdominal wall either the intestinal herniation is not completed then the child will be born

with an open abdomen it is not an umbilical hernia it is not a separation of the wall it is

actually a persistant covering of the amnion, so it requires an immediate surgical invention to

recover it and usually we recover it by certain graft what we call it omphalocele, hernia is a

different bulging because hernia is cover normally by a subcutaneous tissue and the skin and

it is common during the physiological herniation of the stomach of the mid gut and there

return .

The END

Done by: amen al-beek

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20

Anatomy

Lymphatic drainage and nerve supply

Saleh Bani-Hani

Dalia Rawashdeh

Tuesday, 15/11/2011

1

The Lymphatic Drainage and Nerve Supply

Today we will talk about the lymphatics and the innervations of the GIT.

But before that we have to review the blood supply, because the lymph

vessels and the nerves fibers follow the blood supply.

Now, the blood supply:

We have three parts. They are all branch from the abdominal aorta.

1. Celiac artery: it has three branches.

i. Left gastric artery: supplies the right part of the stomach

(lesser curvature) and the cardia and the lower esophagus.

ii. Splenic artery: it runs behind the stomach to the spleen but

before reaching the spleen, it gives a) short gastric artery b)

left gastroepiploic artery.

iii. Hepatic artery: a) the right gastric artery that will

anastomose with the left gastric. b) the gastroduodenal

artery: it descends behind the first part of the duodenum

and terminates as two branches the right gastroepiploic

artery and the second one is the superior

pancreaticoduodenal artery ((which supply the upper part

of the duodenum and the pancreas)). c) The cystic artery d)

Right and left hepatic artery.

So the celiac artery supplies the stomach, lower esophagus, spleen,

upper part of the pancreas, upper part of the duodenum and the liver.

2. Superior mesenteric:

i. Inferior pancreaticoduodenal artery

ii. Right colic artery: gives the ascending and the descending

parts

iii. Middle colic artery: gives the right and the left parts.

iv. Iliocolic artery

v. Jejunal and ileal arteries

So the superior mesenteric artery supplies the small intestine (part of the

duodenum), part of the pancreas, cecum, appendix, ascending colon and

part of the transverse colon.

2

3. The rest part of the GIT is supplied by the inferior mesenteric

artery.

The Lymphatic Drainage:

When we come to the lymphatic drainage, we have main groups of

lymphatic nodes that are located around the origin of these three main

arteries: a) celiac lymph nodes b) superior mesenteric lymph nodes c)

inferior mesenteric lymph nodes.

For example: the lymph drainage of the stomach:

We have left gastric lymph nodes, short gastric lymph nodes and left and

right gastroepiploic lymph nodes and so on. (All of them are related to

the arteries). So the lymph of the stomach will go to these small lymph

nodes. Now from these lymph nodes lymph vessels will carry lymph to

the main nodes, the celiac lymph nodes.

The lymph drainage of the pancreas and the duodenum are similar to

the blood supply. For example we have pancreaticoduodenal lymph

nodes from them lymph vessels will ascend and descend. Now from the

upper part of the pancreas and the duodenum lymph vessels carry

lymph to the gastroduodenal lymph nodes (the same name of the

artery). And from the gastroduodenal lymph nodes lymph will go to the

celiac lymph nodes.

**Upper part of the pancreas and the duodenum to the celiac lymph

nodes.

The liver is the most active organ in lymph production. It produces from

one third to one half of the lymph in our body. Lymph from the liver will

go to the lymph nodes at the hilum of the liver. We also have cystic

lymph nodes around the cystic artery then it will go to the hepatic lymph

nodes which will carry the lymph to the celiac lymph nodes.

So the celiac lymph nodes will receive lymph from the same structures

which are supplied by the branches of the celiac artery.

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The same thing is for the lymphatic drainage for the small intestine. For

example we have jejunal lymph nodes, ileal lymph nodes, and colic

lymph nodes and so on. So from the structures that are supplied by the

superior mesenteric artery (this include the inferior part of the pancreas

and the duodenum, jejunum, ileum, cecum…till the middle of the

transverse colon) all of them will go to the superior mesenteric lymph

nodes.

**the lower pancreas and duodenum drain into the superior

mesenteric lymph nodes.

We have similar drainage to the rest of the GIT. For example, the rectum

will have pararectal lymph nodes which will go to the superior rectal

lymph nodes then to the inferior mesenteric lymph nodes around the

origin of the inferior mesenteric artery.

When we come to other parts of the GIT and look at the lymph nodes:

In the neck we have deep cervical lymph nodes. Those lymph nodes run

along anteroposterior aspect of the internal jugular vein. Now these

lymph nodes receive from other but smaller lymph nodes, which include

parotid lymph nodes that receive lymph from the parotid gland which go

to the deep cervical lymph nodes.

Submandibular lymph nodes are located in the submandibular triangle

at the superficial surface of the submandibular salivary gland.

The submandibular lymph node receives lymph from the anterior 2/3 of

the tongue except the tip of the tongue. And receive lymph from the

floor and from the vestibule of the oral cavity except the small part on

each side of the midline on the floor. Because lymph that is coming from

the tip of the tongue and lateral sides of the midline in the floor goes to

the submental lymph node, which is located in the submental triangle

between the anterior bellies of the two digastric muscles.

So these small lymph nodes that drain parts of our GIT will go to the

deep cervical lymph nodes.

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We have two clinically important subgroups coming from the deep

cervical. One of them is called jugulodigastric lymph nodes (we call it

this because it is located along the posterior belly of the digastric

muscle). The second one is juguloomohyoid lymph nodes from the

name they are related to the omohyoid muscle.

These two groups are important because they receive lymph from the

tongue and tonsils.

Nerve supply:

We have two nerve plexuses within the GIT wall. They form the enteric

nervous system. They are: the myenteric plexus and the submucosal

plexus.

Now, what are the differences between them in terms of function and

location?

The myenteric plexus: it is located between the two layers of the

muscularis. ((Between the inner circular layer and the outer longitudinal

layer)).It is responsible for the movement of the wall of the GIT like

peristalsis.

The submucosal plexus: it is smaller and has other functions mainly

related to mucus membrane and muscularis mucosa and in controlling

the secretion of the gastrointestinal glands.

There is large number of neurons within these two plexuses. Some of

them are excitatory and others are inhibitory. And some are motor and

others are sensory.

The Enteric nervous system is under the control of the autonomic

nervous system (both sympathetic and parasympathetic). Also the

enteric NS is affected by hormones. For example the pylorus produces

two hormones. The first one is 1)Gastrin which keeps the motor activity

and 2)Somatostatin which inhibits it.

So Enteric NS consists of two plexuses of neurons in the wall of GIT. (The

myenteric plexus and the submucosal plexus).And is controlled by

autonomic NS and hormones.

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In this lecture we will discuss the autonomic NS

Again the sympathetic and the parasympathetic fibers will follow the

blood vessels.

So we have celiac nervous plexuses around the origin of the celiac

artery, superior mesenteric nervous plexuses and inferior mesenteric

nervous plexuses. We have other nervous plexuses related to other

organs in other systems.

Now these celiac nervous plexuses receive preganglionic autonomic

(both sympathetic and parasympathetic) then these nerves cells send

their postganglionic to supply the same structures which are supplied by

the celiac artery. Ya3nii these fibers of the autonomic NS will follow the

blood vessels. The same thing is true concerning the superior and

inferior mesenteric plexuses. Again and again these plexuses will receive

the preganglionic then their postganglionic will follow the blood supply.

And that was just an introduction.

We will start with the sympathetic nervous system.

Now as you know the sympathetic NS has preganglionic and

postganglionic fibers. The preganglionic sympathetic fibers arrive from

the sympathetic cord of the spinal cord between the levels of T1-L2.

***here the doctor is telling us what we have in the figure that is in

the slides:

Here we have the spinal cord, medulla, pones, and the midbrain. Now on

each side of the spinal cord we have the sympathetic chain which

extends from the upper part of the neck to the lower part of the pelvis.

One chain is on each side of the spinal cord.

Sympathetic chain:

In the cervical area of the sympathetic chain we have three

preganglions; superior, middle and inferior sympathetic preganglions.

Also we have in the thoracic area about 11 thoracic preganglions. And 4-

5 lumber and 4-5 sacral sympathetic preganglions.

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Now the preganglionic sympathetic fibers which arise from T1 segment

of the spinal cord will go to the superior cervical ganglion to make

synapses with nerve cells in this ganglion. The nerve cells in the superior

cervical ganglion will send their postganglionic sympathetic fibers which

will run along the internal and external carotid artery to reach and

supply all the involuntary structures in the head and neck. (We mean by

involuntary structures; smooth muscles that line the blood vessels and

the glands).

Now the preganglionic sympathetic fibers which arise from T1-T5 go to

the sympathetic chain and terminate within the superior, middle,

inferior cervical ganglion and also within the upper thoracic sympathetic

ganglions. Now both fibers from the cervical and upper thoracic will run

to supply different organs in our thoracic cavity. For example cardiac

nervous plexuses that supply the heart and the pulmonary nervous

plexuses that supply the bronchial tree.

**Note: keep in mind that the T1 segment goes to the superior cervical

ganglion specifically whether in the T1 segment alone or from T1-T5 as a

group.

Now for the sympathetic fibers that supply the GIT, they will run through

the sympathetic chain without making synapses within the sympathetic

chain. They arise from spinal cord between T5-L2. Mainly they are from

the thoracic segment.

From preganglionic fibers T5-T9: they will run through the sympathetic

chain without making synapses and then form the greater splanchnic

nerve which passes through the diaphragm to terminate and make

synapses with the nerve cells of the celiac plexuses that is found around

the origin of the celiac artery. Then the postganglionic of these celiac

plexuses will follow the branches of the celiac artery and supply the

same structures which are supplied by the celiac artery.

From preganglionic T10-T11:they form the lesser splanchnic nerve which

passes through the diaphragm to make synapses within the superior

mesenteric plexuses that is found around the origin of the superior

mesenteric artery. Then the postganglionic of these superior mesenteric

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plexuses will follow the branches of the superior mesenteric artery and

supply the same structures which are supplied by the superior

mesenteric artery.

From T12: the least splanchnic nerve, it is not related to our GIT but is

related to the urinary system.

From preganglionic L1-L2: they form the pelvic splanchnic nerve and

terminates in the inferior mesenteric plexuses. Then the postganglionic

of these inferior mesenteric plexuses will follow the branches of the

inferior mesenteric artery and supply the same structures which are

supplied by the inferior mesenteric artery.

Always remember that when we talk about the sympathetic NS we

usually talk about the involuntary organs, but also these nerves contain

sensory parts which carry sensory information from these organs to the

spinal cord especially the pain sensation. So most of the pain from our

organs runs with the sympathetic fibers in the opposite direction(the

sensory fibers from the organ to the spinal cord, while the sympathetic

from the spinal cord to the organ).

Parasympathetic:

The parasympathetic has cranial and sacral parts. The cranial part runs

with four cranial nerves and not all of them are related to the digestive

system.

The parasympathetic nerve fiber of the cranial nerve VII (the facial)

supplies the submandibular and the sublingual salivary glands. Also it

contains taste buds (which mean sensory fibers) that are found in the

anterior 2/3 of the tongue.

Some of the cranial nerves are sensory or motor and some others are

mixed.

The next nerve which is IX (the glossopharyngeal): it has sensory and

parasympathetic fibers which are related to the GIT. The

parasympathetic fibers supply the large salivary gland which is the

parotid.

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Note: the parasympathetic NS has preganglionic and postganglionic like

the sympathetic NS. For example the parasympathetic preganglionic

facial nerve terminates in the submandibular and sublingual ganglion.

Then the postganglionic fibers that arise from these two ganglions

(submandibular and sublingual) supply the submandibular and

sublingual salivary glands.

The preganglionic of the glossopharyngeal nerve goes to the otic

ganglion which is located just below the foramen ovale. Then the

postganglionic fibers which arise from the otic ganglion will form

another nerve which is called the auriculotemporal nerve which supplies

the parotid gland and other structures.

The glossopharyngeal nerve supplies the posterior structures of the oral

cavity. (Which includes the oropharynx, tonsils, posterior part of the

tongue, the most posterior part of the soft palate and so on).

The glossopharyngeal sensory nerve supplies the carotid body and the

carotid sinus. The carotid body contains the chemoreceptor and the

carotid sinus contains the baroreceptor and both of them are sensitive

for the change in the blood pressure.

The vagus: it is the only cranial nerve that supplies structures outside the

head and the neck.

So it supplies the involuntary structures that are found in the thorax and

the abdomen till the half of the transverse colon.

*Note: from the previous lectures, keep in mind that the its not till the

half of the transverse colon but till the first 2/3rds.

Again it will contain both parasympathetic nerves and sensory nerves,

which will carry sensation from the wall of the stomach to the

brainstem. For example when we eat there will be distention of the wall

so this will send signals which are carried by the sensory part of vagus to

the brainstem.

Now S2, S3, S4 will carry the parasympathetic fibers to the rest of the

GIT from the middle part of the transverse colon.

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Finally the action:

What is the action of the parasympathetic NS on the wall of the stomach

and the pyloric sphincter?

In general, the parasympathetic is excitatory for the GIT. Now it will

excite the wall of the stomach and inhibits the sphincter in order not to

increase the pressure. Another example is the urinary bladder, the

parasympathetic will be excitatory for the wall and inhibitory for the

sphincter.

While the sympathetic NS will inhibit the wall and will stimulate the

sphincter.

In general the sympathetic NS is excitatory except in three systems

which are; the respiratory system, the urinary system and the digestive

system. Now why is it inhibitory in the RS? Because it will dilate the

bronchial tree (through inhibition of broncho-constriction) so more

oxygen will enter and that’s what we want in emergency situations.

Now the esophagus will receive nerve supply from vagal trunk. (Note:

further information of the nerve supply of the esophagus is found in the

extra notes below).

External notes:

(The ones which are bold, the appendix and the peritoneum are the

ones the doctor forgot to mention and are required, others are extra just

in case.)

1. Esophagus: lymphatic drainage the upper part into the superior

and posterior mediastinal nodes and from the lower third into

nodes along the left gastric blood vessels and the celiac nodes in

the abdomen. Nerve supply vagal trunk(left vagus lies anterior

and right vagus lies posterior), esophageal plexus, sympathetic

trunk, greater splanchnic nerves.

2. Appendix: lymphatic drainage the lymph drains into nodes in

the mesoappendix and eventually into the superior mesenteric

lymph nodes. Nerve supply the appendix is supplied by the

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sympathetic and vagus nerves from the superior mesenteric

plexus. Afferent nerve fibers concerned with the conduction of

visceral pain from the appendix accompany the sympathetic

nerves and enter the spinal cord at the level of 10th thoracic

segment – this creates pain in the umbilical region as well as in the

appendix in the cases of the appendicitis which is something we

called referred pain.

3. Rectum: lymphatic drainage the lymph passes to the pararectal

nodes and then upward to the inferior mesenteric nodes, some

lymph vessels pass to the internal iliac nodes. Nerve supply

sympathetic and parasympathetic pelvic splanchnic nerves

through the hypogastric plexus.

4. Anal canal: lymphatic drainage from the upper half of the anal

canal ascends to the pararectal nodes and joins the inferior

mesenteric nodes, from the lower half drains into the medial

group of the superficial inguinal nodes. Nerve supply the mucus

membrane of the upper half of the anal canal is sensitive to

stretch and is innervated by fibers that ascend through the

hypogastric plexus, the lower half is sensitive to pain,

temperature, touch, and pressure and is innervated by the inferior

rectal nerves. The internal anal sphincter is supplied by

sympathetic fibers from the inferior hypogastric plexus. The

voluntary external sphincter is supplied by the inferior rectal

nerves.

5. Peritoneum: Nerve supply the parietal peritoneum is supplied

for the sensation of pain, temperature, touch, and pressure by the

lower six thoracic and first lumbar nerves. The parietal

peritoneum in the pelvis is mainly supplied by the obturator

nerve. The visceral peritoneum is supplied for the sensation of

stretch only by autonomic nerves that supply the viscera or that

are travelling in the mesentries.

Done by: Dalia Rawashdeh