THE ABDOMINAL CAVITY 345 



psoas major, after it has been crossed by the root of the mesentery 

 (Fig. 107). The peritoneum over it is carefully incised, and it 

 is then traced downwards and divided. The cut end is then 

 approximated to the descending limb of the pelvic colon, and 

 the implantation is carried out as before. 



In Ileo-Pelvic-Colostomy an anastomosis is established 

 between the terminal part of the ileum and the pelvic colon. 

 The operation is performed in chronic intestinal stasis, or for 

 threatened obstruction in the intervening parts of the large 

 bowel. It is carried out with the pelvis slightly elevated, and 

 good access is obtained by a median infra-umbilical incision. 



Care must be taken to divide the ileum on the proximal side 

 of any obstructing bands (p. 325), and in such a way that it 

 can be connected to the pelvic colon without any subsequent 

 tension on the anastomosis. After the ileum has been cut 

 through, the mesentery is divided very slightly to facilitate the 

 invagination of the distal cut end of the gut. In bringing the 

 ileum into apposition with the pelvic colon, its cut end must be 

 rotated counter-clockwise in order that the left or lower surface 

 of the mesentery may lie in contact with the right surface of the 

 descending limb of the pelvic meso-colon. If the cut end is 

 rotated in the opposite direction, the enteric mesentery is 

 twisted and the ileum may subsequently become kinked. The 

 anastomosis between the cut end of the ileum and the side of 

 the descending limb of the pelvic colon is then completed. As 

 a result the anastomosis forms a bridge in front of a patent 

 passage between the mesentery and the pelvic meso-colon, and 

 in order to prevent the occurrence of an intra - peritoneal 

 strangulated hernia the two mesenteries are closely drawn 

 together by means of a linen-thread purse-string suture. 



Development of the Intestines. The alimentary canal caudal to the 

 stomach elongates much more rapidly than the posterior abdominal wall, 

 and the growth of the mesentery keeps pace with it. A U-shaped loop is 

 thus formed, which passes out of the abdomen through the patent umbilicus 

 (p. 288), carrying down the superior mesenteric artery between the two layers 

 of the mesentery. An evagination appears on the distal limb of the U and 

 subsequently forms the caecum and the vermiform process. Shortly after 

 its appearance the gut becomes rotated round the superior mesenteric artery, 

 so that the distal limb of the loop is carried across the ventral surface of the 

 proximal limb (Fig. 90). When the loop is withdrawn into the abdomen again 

 (p. 288) it is found that, as a result of this rotation, the transverse colon 

 crosses in front of the duodenum. 



Thereafter, the mesentery of the large intestine partially disappears and 

 only persists for the transverse and pelvic cola. After the rotation the 

 transverse colon lies behind the greater omentum (p. 303), and its mesentery 



