CorpusHuman Anatomy
DigestiveMembrane

Greater omentum

Omentum majus

Also known as: gastrocolic ligament, gastrosplenic ligament, epiploon

The greater omentum is a large, fatty, four-layered fold of peritoneum that hangs like an apron from the greater curvature of the stomach over the intestines, then folds back up to attach to the transverse colon.

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Overview

The two layers of peritoneum covering the front and back of the stomach meet at the greater curvature and descend as the anterior two layers of the apron. They then turn back upwards as the posterior two layers to enclose the transverse colon and blend with the transverse mesocolon. In adults the layers usually fuse, obliterating the inferior recess of the lesser sac. The part between the stomach and transverse colon is the gastrocolic ligament. To the left, the omentum continues as the gastrosplenic ligament (carrying the short gastric and left gastro-omental vessels) and the gastrophrenic ligament.

The omentum contains variable amounts of fat, the right and left gastro-omental vessels forming an arcade along the greater curvature, lymph nodes, and milky spots. Milky spots are clusters of macrophages and lymphocytes that clear particles and bacteria from peritoneal fluid. The omentum is carried by peristalsis and adheres where the peritoneum is inflamed. It walls off infections such as an appendix mass or a perforated ulcer, which has earned it the name "policeman of the abdomen".

Location

Hangs from the greater curvature of the stomach and proximal duodenum in front of the transverse colon and small intestine. The posterior layers attach to the transverse colon.

Parts & subdivisions

  1. Gastrocolic ligament
    Part between the greater curvature and the transverse colon. Divided to enter the lesser sac.
  2. Gastrosplenic ligament
    To the splenic hilum; carries the short gastric and left gastro-omental vessels.
  3. Gastrophrenic ligament
    From the fundus to the diaphragm.

Anatomy

Arterial supply

Omental branches of the right gastro-omental (from the gastroduodenal) and left gastro-omental (from the splenic) arteries.

Venous drainage

Gastro-omental veins → SMV and splenic vein → portal vein.

Lymphatic drainage

Gastro-omental nodes → pyloric and pancreaticosplenic nodes → coeliac nodes.

Development

Derived from the dorsal mesogastrium, which balloons out to the left and downwards as the stomach rotates.

Function

  • Immune defence and walling-off of infection (milky spots, adhesion to inflamed sites).
  • Fat storage; visceral adiposity is metabolically active.
  • Mechanical protection and insulation of the intestines.
  • Revascularisation of injured areas and a source of vascularised tissue for repairs.

Clinical significance

Omental patch and omentoplasty

A perforated duodenal ulcer is often closed with a pedicle of omentum (Graham patch). Omental flaps are also used to fill dead space and bring blood supply to difficult wounds.

Omental "cake"

Diffuse metastatic infiltration of the omentum, typical of ovarian and gastric carcinoma. It produces a palpable upper abdominal mass and ascites.

Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.