omento

The omentum is a fold of peritoneum that connects the stomach and proximal duodenum with other abdominal organs. It consists of two main structures: the greater omentum, a large apron-like fold that hangs from the greater curvature of the stomach and drapes over the intestines; and the lesser omentum, a smaller sheet that extends from the liver to the lesser curvature of the stomach and the first part of the duodenum.

The greater omentum develops from the dorsal mesogastrium, while the lesser omentum originates from the ventral mesogastrium. The lesser omentum includes the hepatogastric and hepatoduodenal ligaments, through which the portal triad (hepatic artery proper, portal vein, and common bile duct) travels to reach the liver. The greater omentum contains fat, connective tissue, vessels, lymphatics, and folds called appendices epiploicae.

Functions include immune and mechanical roles: it can migrate to sites of infection and inflammation to limit spread, walling off areas, and it provides cushioning and fat storage. Milky spots, clusters of macrophages within the omentum, contribute to peritoneal immunity.

Clinical relevance: Omental pathology includes infarction or torsion, which can cause acute abdominal pain. In surgery, the omentum can be used in reconstructive procedures (omentoplasty or omental flap) to promote healing or seal leaks. Its mobility allows it to adapt to disease processes within the peritoneal cavity.