322 THE ABDOMEN AND PELVIS 



that the same procedure may be carried out with regard to the gastro-splenic 

 ligament. 



It may not be possible to carry out the second method if perisplenitis has 

 caused adhesions to form between the spleen and the diaphragm. 



Small Intestine. The freely movable part of the small 

 intestine extends from the duodeno-jejunal flexure to the 

 caecum. The upper two-fifths constitutes the jejunum and 

 the lower three-fifths the ileum, but there is no definite line of 

 demarcation. These two parts of the alimentary canal together 

 measure about twenty-three feet, and they are suspended from 

 the posterior abdominal wall by the mesentery, which gives 

 them an almost complete investment of peritoneum. The coils 

 of the jejunum and ileum occupy the infra-colic compartments 

 and the pelvis, and are usually covered over by the greater 

 omentum. In most cases the first loop of the jejunum can be 

 found on the anterior surface of the left kidney, near its lower 

 pole, while the lowest loop of the ileum lies in the pelvis. 



The Mesentery. The root of the mesentery begins on the 

 anterior surface of the fourth part of the duodenum in front of 

 the left side of the second lumbar vertebra, and extends down- 

 wards and to the right. It crosses, successively, in front of 

 the third part of the duodenum, the aorta, the inferior vena 

 cava, the right ureter and the psoas major, and terminates in 

 the right iliac fossa at the ileo-caecal junction. This line of 

 attachment is only six or seven inches in length, and, in order 

 to enclose the twenty-three feet of intestine, the mesentery 

 spreads out in a fan-shaped manner and becomes very much 

 pleated near the gut. Its depth varies, being as much as seven 

 or eight inches at its deepest part. The two peritoneal layers of 

 which it consists contain between them nerves, blood-vessels, 

 lymph vessels (lacteals) and glands, and a varying amount of 

 fat. The latter is more thickly deposited along the root, and it 

 diminishes in quantity as the mesentery is traced to the intestine. 

 This feature is much better marked in the upper than in the 

 lower end of the mesentery, and, when it is examined near the 

 duodeno-jejunal flexure, semi-translucent peritoneal " windows " 

 can be seen, separated from one another by branches of 

 the superior mesenteric artery (Fig. 100). These " windows " 

 become more obscure as the jejunum is traced downwards, and, 

 in the lower part of the ileum, they cannot be distinguished 

 owing to the larger deposition of fat near the gut (Fig. 101). 

 By the examination of the mesentery, therefore, it may be 



