As the stomach and the duodenum become rotated, the lesser sac extends to the left. The caudal part of the mesogastrium is attached to the greater curvature of the stomach and grows in a caudal direction. Consequently, this part of the dorsal mesogastrium forms an apron-like mesenteric fold: the greater omentum (omentum majus). This fold is just an extension of the lesser sac. The layers of the greater omentum gradually fuse together. The part that is fixed to the transverse mesocolon amalgamates with the dorsal abdominal wall and with the transverse mesocolon (mesocolon transversum).
Rotation of the stomach and the duodenum also causes the lesser omentum (omentum minus) to lie in the frontal plane. Thus, it covers the lesser sac ventrally.