THE BODY CAVITIES, DIAPHRAGM AND MESENTERIES 



IQI 



peritoneal cavity. Thus the cavity of the lesser peritoneal sac is ex- 

 tended caudally from a point opposite the bifurcation of the lungs to the 

 level of the pyloric end of the stomach. In 5 to 10 mm. embryos it is 

 crescent-shaped in cross section (cf. Fig. m) and is bounded mesially 

 by the greater omen turn (dorsal mesentery) and the right wall of the 

 stomach, laterally by the liver and plica venae cavae, and ventrally by the 

 lesser omentum (ventral mesentery). It communicates to the right 



Suprarenal gland 



Liver 



Lesser peritoneal sac 

 Duodenum 



Vitelline vein 

 Intestinal loop 



Mesonephros 

 Greater omenti 

 Stomach 



Left umbilical vein 



FIG. 201. An obliquely transverse section through a 10 mm. human embryo at the level of 

 the epiploi.c foramen (of Winslow). X 33- 



with the peritoneal cavity through an opening between the liver ventrally 

 and the plica venas cavas dorsally (Figs. 181 and 201). This opening is 

 the e pi ploic foramen (of Winslow). When the dorsal wall of the stomach 

 rotates to the left, the greater omentum is carried with it to the left of its 

 dorsal attachment. Its tissue grows actively to the left and caudally 

 and gives the omentum an appearance of being folded on itself between 

 the stomach and the dorsal body wall (Fig. 200). The cavity of the 

 lesser peritoneal sac is carried out between the folds of the greater omentum 

 as the inferior recess of the omental bursa. 



From the cranial end of the sac there is constricted off a small closed cavity which is 

 frequently persistent in the adult. This is the bursa infracardiaca and may be regarded 

 as a third pleural cavity. It lies at the right of the esophagus in the mediastinum. 



