Peritoneum and Peritoneal cavity

Lecture 13.

Dr. Mohammad Muzammil AhmedAssistant Professor of Anatomy and

Embryology

OBJECTIVESEnlist functions of peritoneumDiscuss the development of peritoneum and

peritoneal cavityIdentify general arrangement of peritoneal visceraDescribe modifications of peritoneumEnumerate cavities and compartments of peritoneumIdentify clinical applications (peritonitis, peritoneal

pain, peritoneal dialysis and internal abdominal hernia)

Suggested reading: Clinical Anatomy by Region 9th edition, page 160-168

Peritoneum It is a thin, serous, continuous

glistening membrane lining the abdominal & pelvic walls and clothing the abdominal and pelvic viscera.

Parietal layer lines the wall & visceral layer covers the organs.

The potential space between the two layers is filled with very thin film of serous fluid to facilitate the movement of the abdominal organs.

Peritoneal cavity is the largest cavity in the body.

The surface area of parietal & visceral layers is enormous.

The peritoneal cavityIt is divided into two main

sacs:1- Greater sac.2- Lesser sac or omental bursa.These two sacs are

interconnected by a single oval opening called the epiploic foramen or opening into lesser sac or foramen of Winslow

Intraperitoneal And Retroperitoneal Relationships

Intraperitoneal organ means that the organ is completely covered by visceral layer of peritoneum e.g. stomach, jejunum, ileum & spleen.

N.B. No organ lies inside the peritoneal cavity.

Retroperitoneal organ means that the organ lies behind the peritoneum and partially covered by visceral peritoneum e.g. pancreas, ascending & descending colon.

Falciform Ligament A sickle-shaped fold of

peritoneum connects the anterior abdominal wall with the liver slightly to the right of the median plane.

Anterior border: Attached to under surface of diaphragm & anterior abdominal wall.

Posterior border: Attached to superior & anterior surfaces of liver

Free margin connects the umbilicus to liver, it contains the round ligament of the liver or Ligamentum teres.

Peritoneal ligaments

Greater sacIt is the part of

peritoneal cavity which lies behind the anterior abdominal wall.

Peritoneum lines the anterior abdominal wall then the under surface of diaphragm, from where it is reflected on to superior surface of liver forming the upper layer of coronary ligament

Then, it descends from superior surface of liver to anterior surface then inferior surface of liver.

From posterior part of inferior surface peritoneum reflected on to front of right kidney & right suprarenal gland forming the lower layer of coronary ligament.

The lower & upper layers of coronary ligament bound a large area on the posterior surface of the liver called bare area of the liver which has no peritoneal covering.

Ligaments of peritoneum attached to liver

Falciform, coronary, right & left triangular ligaments

OmentaTwo layers of

peritoneum that connect stomach to other visceral organs.

Lesser & greater omenta and gastrosplenic omentum (ligament).

Mesentery Two layers of peritoneum

connecting small intestine to post abdominal wall.

It has 2 borders 1- Attached border: to post

abdominal wall & 2- Free border: which

encloses the jejunum & ileum.

Vessels, nerves. Lymphatic enter small intestine between the two layers.

Similarly mesocolon is the peritoneum for the large intestine for eg. Transverse mesocolon, sigmoid mesocolon

Greater OmentumConnects the greater

curvature of the stomach to transverse colon.

It hangs like an apron in front of the small intestine

It is folded back on itself to be attached to the transverse colon.

Lesser OmentumConnects liver to stomach

attached above to porta hepatis & fissure for ligamentum venosum inferiorly to lesser curvature of the stomach,& 1st inch of duodenum.

Its free margin contains:Portal vein: PosteriorBile duct : Anterior & rightHapatic artery: anterior

&left Gastrosplenic ligament

Connects the stomach to the hilum of the spleenSplenicorenal or lienorenal

ligamentConnects the hilum of spleen

to front of the left kidney.

Lesser sacA peritoneal pouch lies

behind stomach & lesser omentum

It projects upwards as far as the diaphragm.

Inferiorly it lies within the folding of the greater omentum.

Its lower part is usually obliterated due to fusion of the anterior & post layers of the greater omentum.

Anterior wall: from above downward

lesser omentum, back of stomach & anterior 2 layers of greater omentum.

Posterior wall: From below upwards, posterior 2 layers of greater omentum, then the peritoneum which covers many structures on posterior abdominal wall

These structures are:1- Body of pancreas.2- Part of abdominal aorta3- Coeliac artery & its

branches (splenic, Leftt gastric & hepatic arteries)

4- Left crus of diaphragm.5- Left kidney.6- Left suprarenal gland.7- Part of inferior phrenic

artery.Upper border: Extends

from porta hepatis, fissure for ligamentum venosum to lower end of esophagus.

Lower border: Inferior margin of greater omentum.

Left border: Left margin of greater omentum, gastrosplenic & lienorenal ligaments.

Right border: Right Margin of greater omentum, opening into lesser sac.

Epiploic Foramen: BoundariesAnterior: free margin of lesser omentum, containing (hepatic artery, bile duct and portal vein)Posterior: peritoneum covering Inferior Venacava.Superior: Caudate process of the caudate lobe of the liver.Inferior: 1st inch of the1st part of duodenum.

Peritoneal Recesses, Spaces,and GuttersDuodenal Recesses

there may be four small pocket like pouches of peritoneum called the superior duodenal, inferiorduodenal, paraduodenal,and retroduodenal recesses.

Cecal Recesses three peritoneal recesses called the superior ileocecal, the inferior ileocecal, and the retrocecal recesses.

Intersigmoid RecessThe intersigmoid recess is situated at

the apex of the inverted,V-shaped root of the sigmoid mesocolon its mouth opens downward.

Subphrenic SpacesThe right and left anterior

subphrenic spaces lie between the diaphragm and the liver, on each side of the falciform Ligament. The right posterior subphrenic space lies between the right lobe of the liver, the right kidney, and the right colic flexure. The right extraperitoneal space lies between the layers of the coronary ligament and is therefore situated between the liver and the diaphragm.

The paracolic gutters lies lateral and medial to the ascending and descending colon respectively.

Function of peritoneum

It suspend the organs within the peritoneal cavity.It fixes some organs within the abdominal cavity.

Storage of large amount of fat in the peritoneal ligaments (e.g.. Greater omentum)Peritoneal covering of intestine tends to stick together in infection Greater omentum is called the policeman of abdomen to prevent spread of infectionIt secretes the peritoneal fluid which helps in the gliding of the mobile viscera over one another.

Innervation of peritoneum:

Parietal peritoneum is sensitive to pain, pressure, temperature & touch,(pptt)

Parietal peritoneum is supplied by:

Lower 6 thoracic nerves (T7-- T12)

First lumber nerve ( L1)Central part of

diaphragmatic parietal peritoneum is supplied by Phrenic nerve. Peripherally supplied by lower 6 thoracic nerves and in the pelvis supplied by the Obturator nerve.

Visceral peritoneum is sensitive to stretch & tearing.

It is supplied by autonomic afferent nerves which supply the viscera.

Development of peritoneum and peritoneal cavityThe peritoneum develops

from the lateral plate mesoderm.

The lateral plate mesoderm splits to form 2 layers- the parietal(somatic)layer and the visceral (splanchnic) layer

The visceral and the parietal layers becomes continuous with each other as the dorsal mesentry, Ventral mesentry is derived from the thinning of the septum transversum.

The peritoneal cavity is derived from that part of the embryonic coelom situated caudal to the septum transversum.

Ascites: Is the excessive accumulation of the peritoneal fluid within the peritoneal cavity.

. The infection may spread into the peritoneal cavity and cause inflammation of the peritoneum which is called as peritonitis. The infected fluid may tend to collect in the most dependent area of the peritoneal cavity in supine position, these areas are pelvis and the right subphrenic space. In such condition the patient complains of pain in the shoulder.

Peritoneal Pain: abdominal pain arising due to the parietal peritoneum can be localised as it is supplied by the somatic nerves T7-T12 and L1. An inflamed parietal peritoneum is extremely sensitive to stretching. This fact is made use of clinically in diagnosing peritonitis. Pressure is applied to the abdominal wall with a single finger over the site of the inflammation. The pressure is then removed by suddenly withdrawing the finger. The abdominal wall rebounds, resulting in extreme local pain, which is known as rebound tenderness

Applied anatomy

Pain arising from the visceral peritoneum is dull and poorly localized as the visceral peritoneum is supplied by the autonomic nerves.

Peritoneal Dialysis: Because the peritoneum is a semi permeable membrane, it allows rapid bidirectional transfer of substances across itself. Because the surface area of the peritoneum is enormous, this transfer property has been made use of in patients with acute renal insufficiency.

Internal abdominal hernia: occasionally a loop of intestine may enter into the peritoneal pouch or recesses and gets strangulated, this is called as internal abdominal hernia.