Lesser sac

The lesser sac, also known as the omental bursa, is the cavity in the abdomen that is formed by the lesser and greater omentum. Usually found in mammals, it is connected with the greater sac via the omental foramen (previously known as the Foramen of Winslow). In mammals, it is common for the lesser sac to contain considerable amounts of fat.

Lesser sac
Latinbursa omentalis
Anatomical terminology

Anatomic margins

Anterior margin
listed from the top-to-bottom margin: Quadrate lobe of the liver, lesser omentum, stomach, gastrocolic ligament
Lateral margin
listed from the most anterior to the most posterior margin: Gastrosplenic ligament, spleen, phrenicosplenic ligament
Posterior margin
Left kidney and adrenal gland, pancreas
Inferior margin
Greater omentum
Superior margin

If any of the marginal structures rupture their contents could leak into the lesser sac. If the stomach were to rupture on its anterior side though the leak would collect in the greater sac.

The lesser sac is formed during embryogenesis from an infolding of the greater omentum. The open end of the infolding, known as the omental foramen is usually close to the stomach.

Additional images

See also


  1. Shahani RB, Bijlani RS, Dalvi AN, Shah HK, Samsi AB (1994). "Massive upper gastrointestinal haemorrhage due to direct visceral erosion of splenic artery aneurysm". J Postgrad Med. 40: 220–222.
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