Lesser omentum

At a glance

English

Lesser omentum

Latin (TA2)

Omentum minus

System

Digestive

Region

Abdomen

Side

Single, on the midline

About the lesser omentum

A delicate sheet, the lesser omentum connects the liver to the stomach and the start of the duodenum; it is formed where the peritoneum covering the front and back of the stomach meets along the lesser curvature and along the top edge of the duodenal bulb. Those two layers come together and climb as one fold to the liver.

On the liver it is attached along an L-shaped line: across the porta hepatis and down into the deep fissure for the ligamentum venosum. From the upper end of that fissure the attachment continues onto the diaphragm, where its two leaves part to surround the end of the oesophagus. The sheet is usually described in two parts. The broad, thin left part, the hepatogastric ligament, runs to the stomach. The thicker right part, the hepatoduodenal ligament, runs to the duodenum and ends on the right in a free edge.

That free edge carries the main structures entering and leaving the liver: the bile duct on the right, the hepatic artery proper on the left, and the portal vein behind both, with lymph nodes, lymph vessels and the hepatic nerve plexus. Behind the free edge lies the omental (epiploic) foramen, the narrow opening from the main peritoneal cavity into the lesser sac, which sits behind the lesser omentum and stomach. The gastric arteries, right and left, travel with their veins along the gastric attachment.

The free edge is of great practical importance. In heavy bleeding from the liver, a surgeon can squeeze this edge between finger and thumb through the omental foramen to compress the hepatic artery and portal vein (the Pringle manoeuvre). During gallbladder and bile duct operations, the contents of the hepatoduodenal ligament must be identified with care. A stomach ulcer on the back wall may perforate into the lesser sac behind this sheet.

Function and supply

Begins at

Attached to the liver along the porta hepatis and the fissure for the ligamentum venosum, continuing up to the diaphragm.

Ends at

Attached to the stomach's lesser curvature, the abdominal oesophagus and the top edge of the duodenal bulb.

Function

Links the liver to the stomach and duodenum, carries the vessels of the porta hepatis in its free edge, and forms the front wall of the upper lesser sac.

Blood supply

Its own supply comes from small branches of both gastric arteries, right and left, which run between its layers along the lesser curvature.