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lesser sac boundries

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Here is a complete breakdown of the boundaries of the lesser sac (omental bursa):

Lesser Sac (Omental Bursa) - Boundaries

The lesser sac is a smaller subdivision of the peritoneal cavity lying posterior to the stomach and liver. It communicates with the greater sac through a single opening - the omental (epiploic) foramen / foramen of Winslow.
Greater and Lesser Sacs of the Peritoneal Cavity

Walls of the Lesser Sac

WallStructure
AnteriorLesser omentum (hepatogastric + hepatoduodenal ligaments), posterior surface of the stomach, and gastrocolic ligament
PosteriorParietal peritoneum covering the pancreas, left adrenal gland, left kidney, and aorta
SuperiorCaudate lobe of the liver and diaphragm
InferiorTransverse colon and transverse mesocolon
LeftGastrosplenic ligament and splenorenal (lienorenal) ligament
RightOpens into the greater sac via the epiploic foramen

Boundaries of the Epiploic Foramen (Foramen of Winslow)

This is the only natural entrance to the lesser sac:
RelationStructure
AnteriorHepatoduodenal ligament (containing portal vein, hepatic artery proper, and bile duct)
PosteriorInferior vena cava (covered by peritoneum)
SuperiorCaudate lobe of the liver
InferiorFirst part of the duodenum (superior part)

Recesses of the Lesser Sac

The lesser sac has three important recesses:
  1. Superior recess - extends upward between the esophagus and IVC, as far as the gastric fundus; its upper limit is the left triangular ligament of the liver
  2. Splenic (left) recess - extends to the left between the gastrosplenic and splenorenal ligaments toward the spleen
  3. Inferior recess - extends downward between the greater curvature of the stomach and the transverse colon (into the greater omentum)

Clinical Relevance

  • Pancreatic pseudocysts commonly form in the lesser sac, as the pancreas forms its posterior wall. The posterior gastric wall can become the anterior wall of a pseudocyst, allowing transgastric drainage.
  • Fluid collections in the lesser sac (e.g., from pancreatitis or perforated gastric ulcer) are walled off and may not communicate freely with the rest of the peritoneal cavity.
  • The Pringle maneuver (compression of the portal triad to control liver bleeding) exploits the epiploic foramen - a finger is passed posterior to the hepatoduodenal ligament through this foramen.
Sources: Gray's Anatomy for Students, p. 363; Schwartz's Principles of Surgery 11th Ed., p. 1585; Color Atlas of Human Anatomy Vol. 2, p. 373
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