The stomach is a muscular sac derived from the simple fetal gastrointestinal tube. The mucosal lining has specialized cells which secrete strong acids and enzymes to break food down before it passes to the small bowel for absorption and distribution.
The walls are folded into rugae which increase the surface area of the sac. The muscular walls contract to help break up food material.
The greater omentum arises from the greater curvature of the stomach, and the lesser omentum from the lesser curvature; the hepatoduodenal ligament lies at the free edge and contains the extrahepatic biliary ducts.
The stomach lies under the diaphragm and to the left of the liver. The strong pyloric sphincter divides the distal stomach from the duodenum or the first portion of the small intestine.