468 A MANUAL OF ANATOMY. 



nal organs (chiefly the liver), until the colon may be left 

 covered only in front and at the sides (the usual condition), 

 or, less peritoneum being drawn off from the colon, there 

 will be left a distinct mesocolon of varying length. In the 

 same manner the entire attachment of the gut below the 

 stomach is moved to the left. 



As a part of this process of peritoneal alterations the 

 Formation of the Omentum must next be explained. 



It is formed by the pouching to the left and forward of 

 the mesogaster below the spleen and as far as the duo- 

 denum. 



This bag will be composed of two layers of the peri- 

 toneum originally forming the mesogaster. It comes to 

 hang down over the intestines covering them in. In a ver- 

 tical section of the fcetus from before backward, the dilated 

 bag of mesogaster (omentum) is seen to come off from 

 the lower part of the stomach, and after making the down- 

 ward loop, to return to the back of the abdomen, where 

 it is attached : the transverse mesocolon and the mes- 

 entery are attached separately and in this order below the 

 posterior omental attachment. (Diags. 36, 37.) 



As growth goes on, the under layer of omentum is 

 drawn away from the spine and then from the upper part 

 of the colon, while the inner layer comes to rest upon the 

 colon and to form the upper layer of its mesocolon. (Diag. 

 38.) This gives the typical formation seen in the adult 

 vertical anteroposterior sections. If the process is inter- 

 rupted, the foetal condition prevails and the omentum is 

 separate from and above the transverse mesocolon at their 

 posterior attachments. (Diag. 37.) This failure of develop- 

 ment is a predisposing condition to volvulus of the 

 bowel. 



The omentum passing to the colon and becoming attached 



