Lesser omentum

The lesser omentum is a thin, double-layered peritoneal fold that extends primarily from the lesser curvature of the stomach and the initial part of the duodenum to the visceral surface of the liver. It serves as a conduit for vessels, nerves, and lymphatics traveling between the liver and the stomach.

2. Attachments and Components

The lesser omentum is anatomically divided based on its points of attachment:

• Hepatogastric ligament:

  • Connects the liver to the lesser curvature of the stomach.

  • Constitutes the more expansive, membranous portion of the lesser omentum.

• Hepatoduodenal ligament:

  • Connects the liver to the proximal duodenum.

  • Contains critical structures enclosed within the portal triad (portal vein, hepatic artery, bile duct)

These two ligaments form a continuous sheet but can be functionally and surgically distinguished.

3. Topographic Relationships and Function

• Ventral boundary of the omental bursa:

  • The lesser omentum contributes to enclosing the omental bursa, a recess of the peritoneal cavity situated between the stomach and the dorsal abdominal wall.

• Epiploic (omental) foramen:

  • Located caudal to the caudate process of the liver and dorsal to the hepatoduodenal ligament.

  • Serves as a natural communication between the greater and lesser sacs of the peritoneal cavity.

4. Species Variations

• Ruminants (e.g., cattle, sheep, goats):

  • The lesser omentum is relatively smaller than the greater omentum.

  • The hepatogastric portion is less prominent due to the massive size of the forestomachs.

  • It still plays a crucial role in suspending the abomasum.

• Equines:

  • The lesser omentum extends from the lesser curvature of the stomach to the liver, enclosing the bile duct system more superficially than in other species.

  • The omental bursa is well-developed.

• Canines and Felines:

  • The lesser omentum is clearly defined and often more accessible during surgery.

  • The epiploic foramen is clinically significant as an access point for liver biopsies or portosystemic shunt ligation.

• Swine:

  • Similar to other monogastrics but can have a more compact arrangement due to the convoluted nature of the intestines.