50 THE JEJUNUM AND ILEUM. 



rately distended with air, these bodies appear very distinctly in 

 it, dispersed at small distances from each other. In the ileum 

 they appear in small clusters, which often have the appearance 

 of disease. 



No natural line of separation for distinguishing the jejunum 

 and ileum from each other, is to be found ; but these names are 

 still retained ; and, therefore, the rule laid down by Winslow is 

 generally adopted, viz. to name jthe first two-fifths of the tube 

 jejunum, and the remainder ileum. There are, however, some 

 important differences between these portions of the intestine. 



In the jejunum, the valvulae conniventes are so numerous, that 

 they lie in contact with each other, as shingles on the roof of a 

 house ; in the ileum they gradually diminish in number, and 

 finally disappear. In the jejunum, the villi are much stronger 

 than they are in the ileum. 



It is very difficult to acquire a precise idea of the arrangement 

 of this part of the intestinal tube, while it is in the abdomen, 

 especially if it be much distended ; but if it be separated at each 

 extremity from the intestine with which it is connected, and 

 the mesentery cut off from the back of the abdomen, and the 

 whole then spread out upon a flat surface, it will appear, as 

 has been already said, that the intestine is arranged so as to 

 form a semicircle, or large curve ; the concavity of which is 

 opposite to the back of the abdomen, while the convexity 

 presents forward. It will also appear, when thus placed upon 

 a table, that the intestine, while connected with the mesentery, 

 is laid into many folds. It has been supposed, that the middle 

 portion of the mesentery, and the intestine connected with it, 

 is generally in the umbilical region ; and the two portions on 

 the sides of it are in the iliac regions ; but their situation in the 

 abdomen varies considerably at different times. When the 

 viscera of the pelvis are empty, a large portion of the small 



view. 7. The jejunum. 8. The ileum, opening into the colon. 9. The caput 

 coli, or intestinum coecum. 10. The appendicula vermiformis. 11. Ascending 

 colon. The number is placed on one of the three longitudinal bands of mus- 

 cular fibres. 12. Transverse colon. 13. Descending colon. 14. Sigmoid 

 flexure of the colon. 15. The rectum, terminated below by a strong band of 

 its circular muscular fibres forming the internal sphincter to the anus. The 

 dilatation or pouch of the rectum is seen above it. 



