374 PRACTICAL ANATOMY. 



duct near the middle, along its inner side ; the trans- 

 verse portion is about five inches long, and becomes nar- 

 rower, and terminates in the jejunum to the left of the 

 second lumbar vertebra. The jejunum is about eight 

 feet long ; it begins at the duodenum and terminates in 

 the ileum; it is more capacious and more vascular than 

 the ileum. The ileum is a highly convoluted portion of 

 the small intestine ; it is ten to twelve feet long, and ter- 

 minates in the right inguinal region in the caecum. The 

 ileum is the narrowest part of the small intestine ; its 

 walls are thin and less vascular than those of the 

 jejunum. 



The small intestine has four coats, serous, muscular, 

 cellular, and mucous; the ileum, jejunum, and first part 

 of duodenum have a peritoneal investment. The mus- 

 cular coat consists of circular and longitudinal fibres; 

 the cellular coat consists of loose connective tissue. The 

 mucous membrane lining the small intestine is thick, 

 covered by columnar epithelium, and presents for exam- 

 ination : the valvulae conniventes ; villi ; mucous crypts, 

 or follicles of Lieberkiihn ; Brunner's glands, in the 

 duodenum; solitary glands; and agminate glands, forming 

 Fever's patches. The valvulae conniventes are transverse 

 folds of mucous membrane, extending one-third around 

 the intestine, and about one-third inch in depth ; they 

 are found in the second and third parts of the duodenum, 

 throughout the jejunum, and gradually disappear in the 

 upper part of the ileum. The valvulae conniventes are 

 arranged spirally around the interior of the intestines. 

 The villi contain the intestinal termini of the lacteals ; 

 they are about four millions in number, and are scattered 

 throughout the whole length of the small intestine ; they 

 are minute, conical elevations, covered by columnar 

 epithelium, and contain lacteals, blood-vessels, nerves, 



