Abdomen 3

In the name of God

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Peritoneum� Peritoneum

� It is the serous membrane(a type of loose connective tissueand is covered by mesothelium) that lines the abdominal cavity.

• Extensions of the peritoneum form the mesenteries, omentaand • Extensions of the peritoneum form the mesenteries, omentaand ligaments that support the abdominal contents.

• Function:

• To produce fluid to lubricate abdominal viscera

• To enhance immune responses

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Intra pritoneal

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Retro peritoneal

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Layers of peritoneum:

� The peritoneum can be regarded as a balloon into which the organs are pressed from outside.

� Due to this, two layers are formed. One layer lines the walls of the abdominal and pelvic cavities and is called the parietal peritoneum.

� The Inner layer covers the organs is known as the visceral peritoneum.

� The space between the parietal and visceral layers, which is the inside space of the balloon, is called the peritoneal cavity.

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Mesentery

�Ventral mesenter vs�Ventral mesenter vsDorsal mesenter

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Extraperitoneal tissue:

� a layer of connective tissue between the parietal peritoneum and the fascial lining of the abdominal and pelvic walls,

� It varies in amount in different regions.

� In the area of the kidneys, it contains a large amount of fat, which provides support to them. which provides support to them.

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Classification of abdominal structures in relation to peritoneum:

� The abdominal structures, on the basis of their relation with the peritoneum, are classified into three categories:

� Intraperitoneal, Retroperitoneal and Infraperitoneal.

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� Intraperitoneal organs:An organ is almost totally covered with visceral

peritoneum(Stomach)

� Retroperitoneal Organs: An organs which lie behind the peritoneum and are only partially covered with visceral peritoneum and are only partially covered with visceral peritoneum (Aorta)

� Infraperitoneal organs: These are organs which lie inferior to the peritoneum in the pelvis (Urinary bladder)

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�Primary vs secondary retro peritoneal

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Peritoneal development

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Peritoneal development

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Peritoneal development

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Peritoneal development

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Peritoneal ligaments, omenta and mesenteries:

� Ligaments:� Peritoneal ligaments are two layered folds of peritoneum

that connect the viscera to the walls of abdomen.

� Unlike other ligaments of body, they don’t possess thedense fibrous tissue and are therefore unique.

� A good example of peritoneal ligaments is found in liver, whichis connected to the diaphragmby falciform ligament, coronaryligament, and right and left triangular ligaments.

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Peritoneal ligaments:

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� Omenta:

� Omenta are two layered folds of peritoneum that connect the stomach to other viscera. There are three more obvious omenta in human body: Greater omentum, Lesser omentum and Gastrosplenic omentum.

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• Greater omentum:

It connects the greater curvature of the stomach to the transverse colon.

It hangs down like an apron on the coils of the small intestine and is folded back on itself to be attached to the transverse colon.

� Lesser omentum:� Lesser omentum:

It suspends the lesser curvature of the stomach from the fissure of the ligamentumvenosum(fibrous remnant of the ductus venosus of fetal circulation) and porta hepatis.

� Gastrosplenic omentum: As the name suggests, it connects the stomach to the hilumof spleen.

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Peritoneal development

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Peritoneal development

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� Mesenteries:

Mesenteries are two layered folds of peritoneum, which connect the parts of the intestine to the posterior abdominal wall. abdominal wall.

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Greater and lesser sac

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� The ligaments, omenta and mesenteries permit blood vessels, lymphatics and nerves to reach the viscera without having to pierce the peritoneum.

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Peritoneal pouches, recesses, and gutters:Peritoneal pouches, recesses, and gutters:Peritoneal pouches, recesses, and gutters:Peritoneal pouches, recesses, and gutters:

� The peritoneum is a highly folded membrane resulting in formation of lots of pouches, recesses and gutters. Some of the important of them are listed below:

� Pouches:� Lesser Sac� Greater Sac� Recesses:� Recesses:� Duodenal recesses� Cecal recesses� Intersigmoid recesses� Spaces:� Subphrenic spaces� Gutters:� Paracolic gutters

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Pouches:

� The peritoneal cavity is the largest cavity of human body and the surface area of the parietal and visceral layers is enormous.

� Greater Sac: It is the main compartment of the peritoneal cavity and extends from the diaphragm down into the cavity and extends from the diaphragm down into the pelvis.

� Lesser Sac: It is smaller in size and lies behind the stomach. It is in free communication with the greater sac through an oval window called the opening of the lesser sac, or “epiploic foramen”.

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Greater and lesser sac

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IVC

Caudate process of liver

Winslow foramen:•Coledock duct(common)• hepatic artery

1st part of deodenum

• hepatic artery•Portal vain

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Greater and lesser sac

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Greater omentum

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Greater sac

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Descending of Testis

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Inguinal

region

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� Classification of abdominal structures in relation to peritoneum:� The abdominal structures, on the basis of their relation with the peritoneum, are classified into

three categories: Intraperitoneal, Retroperitoneal and Infraperitoneal.� Intraperitoneal organs: An organ is said to be Intraperitoneal when it is almost totally

covered with visceral peritoneum. The Intraperitoneal organs of human body are:� Stomach� First part of duodenum� Jejunum� Ileum� Cecum� Cecum� Appendix� Transverse colon� Sigmoid colon� Upper 1/3 of Rectum� Liver� Spleen� Uterus (Females)� Fallopian tubes (Females)� Ovaries (Females)

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� Retroperitoneal Organs: These are organs which lie behind the peritoneum and are only partially covered with visceral peritoneum. The retroperitoneal organs of human body are:

� Second and third parts of cuodenum� Ascending colon� Descending colon� Middle 1/3 of Rectum� Pancreas� Kidneys� Adrenal glands� Proximal ureters� Proximal ureters� Renal vessels� Gonadal blood vessels� Inferior vena cave� Aorta� Infraperitoneal organs: These are organs which lie inferior to the peritoneum in the

pelvis. These include:� Lower 1/3 of rectum� Urinary bladder� Distal ureters

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