The epiploic foramen (also called the foramen of Winslow) is a passage between the greater sac (peritoneal cavity proper) and the lesser sac (omental bursa), allowing communication between these two spaces.
- anterior: the free edge of the lesser omentum, known as the hepatoduodenal ligament; there are two layers and within these layers are the common bile duct, hepatic artery proper, and portal vein
- posterior: the peritoneum covering the inferior vena cava
- superior: the peritoneum covering the caudate lobe of the liver
- inferior: the peritoneum covering the commencement of the duodenum and the hepatic artery, the latter passing forward below the foramen before ascending between the two layers of the lesser omentum