By :

Dr. Ahmed Salah younes

Introduction :

Greek peritonaion = stretch around

The peritoneum is a continuous serous membrane which lines the abdominal cavity and covers the abdominal organs .

It acts to support the viscera, and provides a pathway for blood vessels and lymph..

The total membrane area includes the visceral peritoneum (60%) , peritoneal covering the mesentery and omental surfaces (30%) and the paritalperitoneum (10%)

Histology : The peritoneal membrane is

comprised of six layers consisting of the

1- capillary fluid film, 2- capillary endothelium, 3- endothelial basement

membrane4- interstitium, 5- mesothelium6- the fluid film .N.B : mesothelium :consist of a

layer of simple squamousepithelial cells

Parts of peritonium The peritoneum consists of : A- the parietal peritoneum

a heterogeneous, serous, semi-permeable membrane that lines the abdominal wall

B- the visceral peritoneumwhich covers the abdominal organs

C- Peritoneal cavity Its surface area is approximately 1-2 m2

In males, the peritoneum is a closed-sac system, whereas in females it is an open-sac system with the fallopian tubes and ovaries connecting to the peritoneal cavity

1- Parietal Peritoneum : The parietal peritoneum lines the

internal surface of the abdominopelvic wall.

It is derived from somatic mesoderm in the embryo.

It receives the same somatic nerve supply as the region of the abdominal wall that it lines, therefore pain from the parietal peritoneum is well localised and it is sensitive to pressure, pain, laceration and temperature.

The parietal peritoneum derives its blood supply from the abdominal wall (lumbar, intercostals, and epigastric regions) and drains into the inferior vena cava, while

2- Visceral Peritoneum :

The visceral peritoneum invaginates to cover the majority of the abdominal viscera.

It is derived from splanchnic mesoderm in the embryo.

the visceral peritoneum receives its blood supply from the superior mesenteric artery and drains into the portal vein. The total peritoneal blood flow ranges from 50–150 mL/min.

The visceral peritoneum has the same nerve supply as the viscera it invests. Unlike the parietal peritoneum, pain from the visceral peritoneum is poorly localised and is only sensitive to stretch and chemical irritation.

3- Peritoneal Cavity : The peritoneal cavity is a potential

space between the parietal and visceral peritoneum. It contains a small amount of lubricating fluid.

The peritoneal cavity located between the parietal and visceral peritoneum2,

contains approximately 100 mL of serous fluid1 and becomes the dialysatecompartment during peritoneal dialysis (PD) from which exchange of solutes with the blood can occur.

The peritoneal cavity is divided broadly in to parts :

A- Greater sac : main large part B- Lesser sac small part situated

behined stomach , lesser omentum & liver

C- two sac communicated through the epiploic foramen (of winslow)

Drainage of the peritoneal cavity is mainly accomplished by the lymphatic system.

Importantly, the subdiaphragmatic lymphatic system is responsible for 70-80% of the lymphatic flow from the peritoneal cavity.

The lymphatic system also serves as a pathway for the removal of foreign substances and macromolecules.

In stable patients undergoing PD, the rate of lymphatic flow varies from 7-20 mL/hr with total fluid losses between 60-91 mL/hr3.

Structures which are formed by peritoneum

1- Omentum: The omentum is a double layer of peritoneum that extends from the

stomach and proximal part of the duodenum to other abdominal organs.

A- Greater Omentum: The greater omentum consists of four layers of peritoneum. It descends

from the greater curvature of the stomach and proximal part of the duodenum, then folds back up and attaches to the anterior surface of the transverse colon.

It has a role in immunity and is sometimes referred to as the ‘abdominal policeman’ because it can migrate to infected viscera.

B- Lesser Omentum : The lesser omentum is considerably

smaller and attaches from the lesser curvature of the stomach and the proximal part of the duodenum to the liver. It consists of two parts:

the hepatogastric ligament and the hepatoduodenal ligament.

C- Omental foramen : Behined the right border of

hepatoduodenal ligament Superior- caudate lobe of liver Inferior – superior part of

duodenum Anterior-hepatodudenal ligament Posterior-peritoneum covering the

inferior vena cava

2- Mesentery A mesentery is double layer of visceral

peritoneum. It connects an intraperitoneal organ to

the (usually) posterior abdominal wall. It provides a pathway for nerves, blood

vessels and lymphatics from the body wall to the viscera.

Mesentery related to the gastrointestinal system is named according to the viscera

A- Mesoappendix : trianguler mesentery from ileum to appendix

B- Transverse mesocolon : transverse colon to posterior abd wall

C- sigmoid mesocolon inverted v shaped with apex located in front of left ureterand division of common iliac artery

3-Peritoneal Ligaments A peritoneal ligament is a double fold of peritoneum that

connects viscera together or connects viscera to the abdominal wall, for example the hepatogastric ligament which connects the liver to the stomach.

A- Ligament of liver :1- Falciform ligament of liver 2- coronary ligament :3- left and right trianguler ligaments 4- hepatogasteic ligamint5- hepatoduodeenal ligament 6- ligamentum tereshepatis

B- ligament of spleen :1- gastro-splenic ligamint :2- splenorenal ligament3- pherenicosplenic ligament 4- spleinocolic ligament

C- Ligaments of stomach :1- Hepatogastric ligament 2- Gasterosplenic ligament 3- Gasteropherenic ligamint4- gasterocolic ligament 5- gasteropancreatic ligament

4- Fold and Recesses of posterior abdominal wall A- superior duodenal fold and recessB- inferior duodenal fold and recess C- intersigmoid recess formed by the inverted V attachment of sigmoid mesocolonD- reterocecal recess E- Hepato-renal recess 5- Fold and fossas of anterior abdominal wall A- median umblical fold :Contain the remnant of urachus (median umblical ligaments)B- medial umblical fold : contain remenant of umblical artery umblicalC- lateral umblical fold :Contain inferior epigasteric vessel D- supravesical fossaE- medial ingiunal fossaF- lateral inguinal fossa

6- Pouches :A- Male : rectovesical pouch B- female :Rectouterine pouch Vesicouterine pouch

Peritoneal subdivisions The transverse colon and transverse mesocolon divides the great sac into :1- supracolic compartment: lie between diaphragmatic and transverse colon and transverse mesocolonB- suprahepatic recess :C- Lt supra hepatic recesses :D- Rt supra- hepatic recesses E- infra hepatic recess ‘

2- infra colic compartment :A- Rt para colic sulcusB- Lt para colic sulcusC- Rt mesentric sinus D- Lt mesentric sinus

Function of the Peritoneum

1- Movement of viscera A- permits peristalsis of stomach and intestine B- Abdominal movement during respiration C- free movement of abdominal viscera

2- Protect of viscera :A- Gaured against infection by phagocyte B- provide celluler & humeral immuonological defense C- greater omentum has the power to move towards site of

infection ((policeman of abdomen ))

3- Absorption :

- It can absorb fluid effusion to blood capillaryies

- The greater absorptiove power of the subpherenic area due to large surface area and respiratory movement

4- Dialysis :

Metabolices like urea can be removed from the blood in PD

Thanks