26 Peritoneal Cavity

STUDYAIMS

At the end of your study, you should be able to:

Understand the difference between the abdominopelvic and peritoneal cavities

Be able to explain the difference between the greater sac and the lesser sac (omental bursa)

Understand the organization of the peritoneal folds that form the greater omentum, lesser omentum, the mesentryof the small intestine, and other mesenteries and peritoneal ligaments

Know which organs are intraperitoneal, retroperitoneal, and secondarilyretroperitoneal Describe the subdivisions of the peritoneal cavity

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GUIDE

Abdomen: Peritoneal Cavity

[Plate 323, Abdominal Wall and Viscera: Paramedian (Parasagittal) Section]

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[Plate 287, Arteries of Small Intestine]

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[Plate 288, Arteries of Large Intestine]

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[Plate 291, Veins of Large Intestine]

Peritoneum

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Serous membrane

Lines the abdominopelvic cavity

Consists of two continuous layers of mesothelium:

Parietal peritoneum

Lines the internal abdominal wall

Receives its neurovascular supplyfrom the region of the wall it lines

Visceral peritoneum

Invests abdominal viscera

Receives its neurovascular supplyfrom that of organ

Peritoneal cavity

Apotential space between the parietal and visceral layers of the peritoneum

Contains a thin film of fluid

No organs actuallylie within this potential space

Males: peritoneal cavityis completelyclosed

Females: communicates with exterior of bodyvia uterine tubes, uterus, and vagina

Intraperitoneal organs

Are organs nearlytotallycovered byvisceral peritoneum

Not actuallyinside the peritoneal cavity, but project into the peritoneal cavity

Are covered byperitoneum

Are attached to bodywall and other organs bymesenteries and ligaments

Include:

Liver

Spleen

Stomach

First part of duodenum

Jejunum

Ileum

Transverse colon

Sigmoid colon

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Superior rectum Primarilyretroperitoneal organs

Organs that develop and remain beneath the parietal peritoneum

Onlythe kidneys Secondarilyretroperitoneal organs

Organs that developed with a short mesentery

Become pushed against parietal peritoneum lining the bodywall bygrowth of other organs, primarilythe small intestine.

Mesenteryof organ fuses with parietal peritoneum: fusion fascia

Peritoneum covers onlyits anterior surface, hence, secondarilyretroperitoneal

Organ can be freed at its lateral edge, along the plane of the fusion fascia

Include

Adrenal glands

Pancreas

Parts two through four of the duodenum Ascending and descending colon

Omenta

[Plate 265, Omental Bursa: Cross Section]

Omentum = double-layered fold of peritoneum

Lesser omentum: connects lesser curve of stomach and proximal duodenum to liver

Passes from the stomach and first part of the duodenum to adjacent organs

Consists of two parts:

Hepatogastric ligament

Hepatoduodenal ligament

Greater omentum

Hangs down from the greater curve of the stomach and proximal duodenum

Folds back on itself to attach to the transverse colon

Mesenteries

Mesentery= double layer of peritoneum created byinvagination of peritoneum byan organ

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Is the continuityof visceral and parietal peritoneum

Provides a pathwayfor neurovascular communication between organ and bodywall

Contains lymph nodes and variable amounts of fat

The mesentery is the mesenteryof the small intestine

The mesocolon is the mesenteryof the large intestine

Transverse mesocolon

Sigmoid mesocolon

Peritoneal ligaments

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Ligament = double layer of peritoneum connecting an organ to another organ or to the abdominal wall

Ligaments of the liver:

Falciform ligament: from liver to anterior abdominal wall

Gastrohepatic ligament

From lesser curvature of stomach to liver

= a portion of lesser omentum

Hepatoduodenal ligament

From the liver to the first part of the duodenum

= Right, thickened free edge of lesser omentum

Contains portal triad (portal vein, hepatic artery, bile duct)

Ligaments of the stomach

Gastrophrenic ligament: from stomach to inferior diaphragmatic surface

Gastrosplenic ligament: from stomach to hilum of spleen

Gastrocolic ligament: from stomach as the greater omentum to the transverse colon

Ligaments of the spleen

Gastrosplenic: from stomach to hilum of spleen

Splenorenal (lienorenal): from spleen to the left kidney

Phrenicocolic ligament (sustentaculum lienis)

From the left hepatic flexure of transverse colon to diaphragm

Supports the spleen

Peritoneal subdivisions

Greater sac: main peritoneal cavity Lesser sac (omental bursa)

Posterior to the stomach

Visible through the lesser omentum

Superior recess: limited bythe diaphragm and posterior layers of the coronaryligament of the liver (Section 4-4: Abdomen-Viscera (Gut))

Inferior recess: potential space between layers of the greater omentum Communicates with the greater sac via the epiploic foramen (of Winslow)

Boundaries of the epiploic foramen

Supracolic compartment

Greater sac above the transverse mesocolon

Contains stomach, liver, and spleen Infracolic compartment

Greater sac below transverse mesocolon,

Contains small bowel, ascending and descending colon.

Divided into left and right divisions bythe mesenteryof the small intestine

Free communication between the supracolic and infracolic compartments via the paracolic gutter

Grooves or recesses between the ascending and descending colon and the posterior abdominal wall along their lateral borders

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