

THE SMALL INTESTINE 



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the lower part of the ileum, it is possible in this way to distinguish the upper 

 from the lower part of the small intestine. 



The Ileum (intestinum Hewn) is narrow, its diameter being 3.75 cm., and its 

 coats thinner and less vascular than those of the jejunum. It possesses but few 

 circular folds, and they are small and disappear entirely toward its lower end, 

 but aggregated lymph nodules (Peyer's patches) are larger and more numerous. 

 The jejunum for the most part occupies the umbilical and left iliac regions, while 



Villi 



Intestinal glands 



Musculans mucosce 



Duodenal glands in 

 submucosa 



Circular muscular layer 



Longitudinal muscular 

 layer 



Serous coat 



FIG. 1058. Section of duodenum of cat. (After Schiifer.) X 60. 



the ileum occupies chiefly the umbilical, hypogastric, right iliac, and pelvic regions. 

 The terminal part of the ileum usually lies in the pelvis, from which it ascends over 

 the right Psoas and right iliac vessels; it ends in the right iliac fossa by opening 

 into the medial side of the commencement of the large intestine. The jejunum 

 and ileum are attached to the posterior abdominal wall by an extensive fold of 

 peritoneum, the mesentery, which allows the freest motion, so that each coil can 

 accommodate itself to changes in form and position. The mesentery is fan-shaped; 



