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)
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Understand the organization of the peritoneal folds that form the greater omentum, lesser omentum, the mesentry of the small intestine, and other mesenteries and peritoneal ligaments
•
Know which organs are intraperitoneal, retroperitoneal, and secondarily retroperitoneal
•
Describe the subdivisions of the peritoneal cavity
Fig. 4-3-1: Longitudinal section through the abdomen to show its shape and superior and inferior boundaries. (From Gosling JA, Harris PF, Whitmore I, et al. Human Anatomy, 4th edition. Mosby, 2005, p. 125, Fig. 4.4)
The greater omentum is often referred to as the “abdominal policeman.” It can move within the peritoneal cavity and wrap itself around an inflamed organ, localizing inflammation and preventing adhesion between the visceral peritoneum and parietal peritoneum of the abdominal wall.
There are several ways to access the omental bursa surgically:
Directly through the lesser omentum
Through the transverse mesocolon
Through the gastrocolic ligament (part of the greater omentum)
Box 4-3-2: Clinical Points
Peritonitis
Inflammation of the peritoneum
Can be localized (e.g., secondary to appendicitis) or generalized (e.g., secondary to bowel perforation)
Can result in reflex tensing (“guarding”) of the overlying abdominal musculature leading to abdominal rigidity.
Involvement of parietal peritoneum leads to well-localized, sharp abdominal pain with tenderness on palpation.
Box 4-3-3: Clinical Points
Ascites
Accumulation of fluid in the peritoneal cavity
May form secondary to peritonitis or a variety of other pathological conditions
Abdomen may become grossly distended as many liters of fluid accumulate
Paracentesis may be undertaken both for diagnostic purposes and for draining the ascitic fluid.
