3 i2 ABDOMEN 



jejunum bends suddenly forwards and downwards from it, 

 forming the duodeno-jejunal flexure. 



The lower coils of the ileum usually lie in the pelvis 

 minor, and the terminal part of the ileum has, as a rule, no 

 great latitude of movement. It ascends from the pelvis 

 minor, across the right external iliac vessels and the corre- 

 sponding psoas major muscle, to join the caecum at the level 

 of the intersection of the intertubercular and right lateral 

 planes. To bring it into view lift the lower coils of the 

 ileum from the pelvis minor and pull them towards the 

 left side. 



The coils formed by the jejunum and ileum are suspended 

 from the posterior wall of the abdomen by a wide fold of 

 peritoneum, called the mesentery. They are thus, for the 

 main part, freely movable within the cavity. Owing to the 

 manner in which the mesentery is attached to the posterior 

 wall of the abdomen (Fig. 138, p. 294), they tend to lie more 

 in the left than in the right portion of the cavity, and they 

 occupy the umbilical, hypogastric, lumbar, and iliac regions, 

 filling up the greater part of the abdominal cavity below the 

 transverse colon and its mesentery. Some of the coils extend 

 downwards into the pelvis minor, and not uncommonly 

 one or more coils of the jejunum may be found in the left 

 hy pochondrium . 



Meckel's Diverticulum. In about 2 per cent, of subjects dissected a 

 blind, hollow protrusion, termed Meckel's diverticulum, juts out at a right 

 angle from the wall of the ileum, at a point rather less than three feet 

 from the junction of the small intestine with the ccecum. It represents 

 a persistent portion of the vitelline duct of the embryo, and under certain 

 circumstances it may lead to conditions which require surgical interference. 



The Mesentery of the Small Intestine. The mesentery 

 of the small intestine is an extensive fold of peritoneum by 

 which the jejunum and ileum are attached to and suspended 

 from the posterior wall of the abdomen. Its posterior border 

 or root is attached along an oblique line which extends, from 

 above downwards and to the right, from the left side of the 

 second lumbar vertebra to the right iliac fossa, crossing in its 

 course the third part of the duodenum, the abdominal aorta, 

 the inferior vena cava, the right ureter, and the right psoas 

 major muscle. This border is about six inches long. The 

 anterior border of the mesentery is attached to the intestine, and 

 is necessarily as long as the part of the gut to which it is attached, 



