106 



TOPOGRAPHICAL ANATOMY OF THE 



stomach is merely a fusiform dilatation of the alimentary tube, the 

 dorsal mesogastrium is short ; but with the disproportionate growth of 

 the dorsal surface of the stomach, whereby the greater curvature is 

 produced, and the rotation of the sac so that its left surface becomes 

 ventral, the mesogastrium gradually assumes a pouch-like form. The 

 greater omentum of the adult develops from part of the wall of the 

 pouch. At first the pouch has a wide mouth directed towards the 

 right ; but with the growth of the liver the mouth of the pouch becomes 

 narrower and is finally reduced to the epiploic foramen. 



As stated above, the dorsal mesentery is at first simple and continu- 

 ous : but the eloneration and rotation of the intestinal tube renders 

 permanence of this simple condition impossible. Hence the complexity 

 met with in the adult. 



Thoracic limb. 



Ventral mesentery 

 Qisophagus 



Stomach. 



Dorsal mesentery. 



1 Dorsal pancreas. 



Ventral pancreas. 



-Pelvic limb. 



Septum transversum. 



Stalk of yolk sac. 



Hind gut. 

 Urinary bladder. 



-Stalk of allantois. 



Fig. 48. — Scheme of the alimentary tract, &c., of an 8-mm. sheep embryo. 



(After Martin.) 



Owing to the large and unwdeldy intestines, a detailed examination 

 of the rest of the peritoneum is not easy in the adult. If opportunity 

 offers, the dissector should examine its disposition in a foal — the 

 smaller the better. 



If the peritoneum that lines the ventral wall of the abdomen be 

 followed forwards in the region of the median plane of the body, it will 

 be found to be continued on to the surface of the diaphragm, and thence, 

 by way of the various hepatic ligaments, to the surface of the liver. 

 From the diaphragm and the liver, the gastro-phrenic ligament and the 

 lesser omentum continue the peritoneum to the lesser curvature of the 

 stomach and the duodenum. After clothing both surfaces of the stomach 

 and duodenum, the peritoneum reaches the greater curvature of the 



