192 



THE ENTODERMAL CANAL AND THE BODY CAVITIES 



When the stomach changes its position and form so that its mid- 

 ventral line becomes the lesser curvature and lies to the right, the position 

 of the lesser omentum is also shifted. From its primitive location in a 

 median sagittal plane, with its free edge directed caudally, it is rotated 

 through 90 until it lies in a coronal plane with its free margin facing 

 to the right (Fig. 201). The epiploic foramen now forms a slit-like 

 opening leading from the peritoneal cavity into the vestibule of the 

 omental bursa. The foramen is bounded ventrally by the edge of the 

 lesser omentum, dorsally by the inferior vena cava, cranially by the 

 caudate process of the liver, and caudally by the wall of the duodenum. 



During fetal life the greater omentum grows rapidly to the left and 

 caudad, in the form of a sac, flattened dorso-ventrally. It overlies the 



ABC 



FIG. 202. Diagrams showing the development of the mesenteries (Hertwig). A illus- 

 trates the beginning of the great omentum and its independence of the transverse mesocolon; 

 in B the two come into contact; in C they have fused. A, stomach; B, transverse colon; C, 

 small intestine; D, duodenum; E, pancreas; F, greater omentum; G, greater sac; H, omental 

 bursa. 



intestines ventrally and contains the inferior recess of the omental bursa 

 (Fig. 202). The dorsal wall of the sac during the fourth month usually 

 fuses with the transverse colon where it overlies the latter (Fig. 202 B). 

 Caudal to this attachment the walls of the greater omentum may be fused 

 and its cavity is then obliterated. The inferior recess of the omental 

 bursa thus may be limited in the adult chiefly to a space between the 

 stomach and the dorsal fold of the greater omentum, which latter is 

 largely fused to the peritoneum of the dorsal body wall. The spleen 

 develops in the cranial portion of the greater omentum and that portion 

 of the omentum which extends between the stomach and spleen is known 

 as the gastro-lienic ligament (Fig. 200). The dorsal wall of the omentum 

 between the spleen and kidney is the lieno-renal ligament. 



