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Lesser sac

Lesser sac

The greater sac or general cavity (red) and lesser sac, or omental bursa (blue).

Horizontal disposition of the peritoneum in the upper part of the abdomen. (Lesser sac is outlined in blue in center.)
Latin	bursa omentalis
Gray's	subject #246 1156
MeSH	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 epiploic foramen (also known as the Foramen of Winslow). In mammals, it is not uncommon for the lesser sac to contain considerable amounts of fat.

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In human anatomy, the wall of the stomach, pancreas and splenic artery^[1] are a part of the wall of the lesser sac. If these structures rupture they may leak into the lesser sac. For the stomach, which lies anterior to the omental bursa, the rupture must be on the posterior side, as if it were anteriorly located, the leak would collect in the greater sac.

The lesser sac is embryologically formed from an infolding of the greater omentum. The open end of the infolding, known as the epiploic foramen, is usually proximal to the stomach.

Additional images

References

^ Shahani RB, Bijlani RS, Dalvi AN, Shah HK, Samsi AB. Massive upper gastrointestinal haemorrhage due to direct visceral erosion of splenic artery aneurysm. J Postgrad Med 1994;40:220-2. Full Text.

v • d • e Peritoneal ligaments, mesenteries, and folds
From ventral mesentery	Lesser omentum: Hepatoduodenal ligament - Hepatogastric ligament Liver: Coronary ligament (Left triangular ligament, Right triangular ligament, Hepatorenal ligament) - Falciform ligament (Round ligament of liver and Ligamentum venosum in it, but not of it)
From dorsal mesentery	Greater omentum: Gastrophrenic ligament - Gastrocolic ligament - Gastrosplenic ligament Mesentery: Transverse mesocolon - Sigmoid mesocolon - Mesoappendix - Root of the mesentery Splenorenal ligament - Phrenicocolic ligament
Uterus/ovaries	Broad ligament of the uterus (Mesovarium, Mesosalpinx, Mesometrium) - Ovarian ligament - Suspensory ligament of the ovary
Folds	Umbilical folds (Supravesical fossa, Medial inguinal fossa, Lateral inguinal fossa) - Ileocecal fold - Rectouterine folds
Recesses	Rectouterine pouch - Vesicouterine excavation - Rectovesical excavation - Pararectal fossa - Paravesical fossa
Peritoneal cavity	Greater sac - Lesser sac - Foramen of Winslow