mouth, larynx and trachea

7/29/2019 Mouth, Larynx and Trachea

1/23

Mouth, Larynx and Trachea

Mouth Just introduction as this is covered in more detail within the gastrointestinal

system.

*Where is it?*Lips to oropharyngeal isthmus [oropharyngeal isthmus lies between the soft palate and the

dorsum of the tongue]

-

*Vestibule vs oral cavity proper

- The vestibule is the cleft between the lips and cheeks externally and the gums and teeth

internally

- Oral cavity proper is bounded by the alveolar arches, teeth and gums, and palate and

tongue


2/23

-

*Need to know boundaries of vestibule

Cheek

*Layers

*skin

*buccopharyngeal fascia

-

*buccinator muscle


3/23

-

*mucous membrane

Floor of the mouth

*Anterior 2/3 tongue

*mucous membrane from tongue to gingiva of mandible

*frenulum

*opening on either side for the submandibular duct - marked by papilla

*sublingual folds extend postero-laterally from papilla

-


4/23

-

Nerve supply

*branches of trigeminal nerve[the fifth cranial nerve also called CN5) is a nerve responsible for

sensation in the face and certain motor functions such as biting and chewing.

Permanent teeth

*2 - incisors


5/23

*1 - canine

*2 - premolars -

*3 - molars third molar called wisdom tooth

Nerve supply teeth

*Mostly pulp [Soft tissue containing the blood and nerve supply to the tooth. The pulp extends

from the crown to the tip of the root.]- rest of tooth has no innervation


6/23

*nerve to periodontal ligament[Made up of thousands of fibres which fasten the cementum to the

bony socket. These fibres anchor the tooth to the jaw bone and act as shock absorbers for the

tooth which is subjected to heavy forces during chewing.]and pulp is shared but is not always

the same as supply to gum

*All branches of the fifth cranial nerve trigeminal

Palate

*Palate is the roof of the mouth in humans and other mammals

separates oral cavity from nasal cavity


7/23

*Hard anterior

Soft posterior

*palatal process of maxilla[ a thick, horizontal process of maxilla. It forms the anterior hard

palate]*horizontal plate of palatine bone [ making up the rest]

*Anterior mucoperiosteum connected via Sharpeys fibres[ matrix of connective tissues

consisting bundles of collagenous fibres connecting periosteum to bone]- indent bone - absent

at horizontal plate


8/23

Tongue

*Mucous membrane on inferior surface of tongue is like most oral mucosa

*Pharyngeal surface (posterior 1/3) of the tongue curves inferiorly and becomes more oriented

more in the vertical plane. Mucosa covering the pharyngeal surface of the tongue is irregular

in contour. There are no papillae on the pharyngeal surface.

Oral and pharyngeal surfaces are separated by a V-shaped terminal sulcus of tongue

At the apex of V-shaped sulcus is a small depression (the foramen caecum of tongue)

*Presulcal (anterior 2/3 anterior to terminal sulcus) stratified squamous epithelium, keratinising,

roughened by papillae


9/23

Anterior ( 2/3)

Papillae in general increase the surface area of contact between the surface of the tongue and

the contents of the oral cavity. All except filiform papillae have taste buds on their surfaces.


10/23

Posterior 1/3

*Part of pharynx see ring of tonsillar tissue including adenoids


11/23

Muscles of the tongue

*Intrinsics are divided into superior longitudinal, inferior longitudinal, transverse and vertical

muscles

- They alter the shape of the tongue by lengthening or shortening it, curling and uncurling

its apex and edges, flattening and rounding its surface.

- Working in pairs or one side at a time the intrinsic muscles of the tongue contribute to

precision movements of the tongue required for speech, eating, and swallowing

-

*Extrinsics muscles also divided into four- genioglossus, hyoglossus, stylogossus and

palatoglossus

- These muscles protrude, retract, depress, and elevate tongue(alter the postion)

Larynx

In the respiratory biology module, we review the larynx from the point of view of respiration. In

the disability module, we review the larynx from the point of view of phonation.


12/23

*Voice box

*Men > women (Adams apple)*Connects pharynx to trachea

*Includes a variety of cartilages

Skeleton of Larynx - 1

*There are three single cartilages

*thyroid, cricoid, epiglottic

*There are three pairs of cartilage

*arytenoid, corniculate & cuneiform

*Finally there are three pairs of joints*cricothyroid, cricoarytenoid, arytenocorniculate


13/23

*As the Thyroid, cricoid and arytenoid cartilages are made of hyaline cartilage, they may ossify.

*Other cartilages are elastic fibrocartilage

*Cricothyroid Joint

*Synovial, capsule

*Axis passes transversely through joints

*Recurrent laryngeal nerve behind this joint

*Cricoarytenoid Joint

*Synovial

*Rotation (opens rima glottis to diamond shape - not much in man) and gliding (opens rima

glottis V shape +++)

Membranes and Ligaments

*Thyrohyoid Membrane

*thickened in midline - median thyrohyoid ligament

*thickened laterally - lateral thyrohyoid ligament

*pierced by inferior laryngeal nerve and superior laryngeal vessels


14/23

*Cricotracheal ligament


15/23

-

*Fibroelastic membranes

*quadrangular membrane is a layer of submucosa. The membrane runs between the

lateral aspects of the epiglottis and arytenoid cartilages on each side.

*vestibular ligaments - lower quad. Membrane.

*cricothyroid ligament - The cricothyroid ligament is the larger part of the laryngealmembrane, continuing inferiorly as a median or anterior part and twin lateral ligaments.


16/23

*

*Laryngeal Inlet

Also known as laryngeal aditus, laryngeal aperture is the opening that connects the pharynx

and the larynx

*

*Faces posterosuperiorly

*Boundaries -

*anterior - epiglottis

*lateral - aryepiglottic fold

*posteroinferior -

*

mucous membrane between arytenoids*corniculate and cuneiform cartilages - small elevations

Vestibule


17/23

*Vestibule - from inlet to vestibular folds

*ant wall - posterior epiglottis

*post wall - arytenoids and their fold containing transverse arytenoid muscles*vestibular fold is mucous membrane covering inferior edge of quadrangular membrane

Laryngeal cavity

- extends from the laryngeal entrance towards the lower border of the cricoid cartilage

where it is continuous with that of the trachea- It is divided into two parts by the projection of the vocal folds, between which is a

narrow triangular fissure or chink, the rima glottidis.

- Laryngeal cavity includes the laryngeal vistubule, middle part of the laryngeal cavity,

laryngeal ventricle and infraglottic cavity


18/23

o Middle and Lower laryngeal cavity

*Middle = Vestibular folds - Vocal folds

*vocal folds are white and contain vocal ligaments - the thickened upper margins of

cricothyroid ligaments

*between vestibular and vocal folds laterally = sinus of larynx

*small diverticulum - saccule of larynx - lubricates*Lower = vocal folds to lower cricoid

*Mucous membrane

*pseudostratified ciliated columnar epithelium (except vocal folds - SS)

Muscles are of 2 types

1) Extrinsic capable ofelevating or depressing the larynx

2) Intrinsic capable ofchanging the shape of the laryngeal inlet or changing the shape of

the aperture created by the vocal cords.

Functions of the Larynx

- 1) Respiration most important function

*2) Sphincter

*a) Inlet


19/23

*b) Rima glottides[the elongated opening between the true vocal cords and between the

arytenoid cartilages] - coughing, sneezing, abdominal straining

*3) Phonation

*a) Pitch - length and tension in vocal ligaments

*b) Quality - resonators - pharynx, mouth & sinuses

Nerves, blood and lymph

*Nerves

*Sensory -

*above vocal folds = superior laryngeal nerve( branch of vagus (X))

*below vocal folds = recurrent laryngeal nerve (branch of vagus (X))

*Motor -

*Intrinsics = Recurrent laryngeal nerve except cricothyroid = external laryngeal nerve


20/23

which arise from superior laryngeal nerve

*Extrinsics - covered elsewhere

*Arteries

-

*Superior laryngeal vessels (STA) upper 1/2

*Inferior laryngeal vessels (ITA) lower 1/2

*Lymph deep cervical node

Trachea

Introduction


21/23

*Larynx - bifurcation into principle bronchi

*9-13cm long*2 - 2.5cm wide

*15 - 20 cartilages

*Each cartilage deficient posteriorly - bridged by trachealis muscle

*C6 to lower manubrium sterni - 5cm lower on deep inspiration!


22/23

*Divided into cervical and thoracic portion

Supply

*Blood -

*Bronchial arteries

*Inferior thyroid arteries

*Inferior thyroid veins / plexus

*Lymph - paratracheal / deep cervical

- The right and left paratracheal lymph nodes (or paratracheal chains) are groups of lymph

nodes located in the throat.

-


23/23

*Nerves -

*Vagus and Recurrent laryngeal nerve (sensory / secretions)

*Sympathetic nervous system (trachealis and blood vessels)

The bronchial branches contain smooth muscle which is under the control of the autonomic

(automatic) nervous system. Stimulation from the sympathetic division of the autonomic nervoussystem causes these smooth muscles to relax, dilating the bronchial branches allowing more air

to pass through the lungs. This is what happens during the "fight or flight" response. When

danger is perceived, the sympathetic nervous system is stimulated to prepare the body for

immediate action. In the case of the lungs, this means allowing more air through so that more

oxygen will be available for muscle contraction (to either fight or run away from the danger

mouth, larynx and trachea

Documents