INTESTINAL CANAL. 35 



with bile, abounds in valvulae conniventes, and about four inches 

 from the pylorus is marked by a small tubercle or elevation, in- 

 dicative of the orifice of the biliary and of the pancreatic duct. 

 The Glands of Brunner are very conspicuous in this inle^stine, 

 and are so numerous near the pyloric orifice, as to form with 

 some a perfect layer, and to give it a granulated appearance 

 for two inches or more. These glands are considered by Mr. 

 Cruveilhier and Boehm to be pancreatic in their structure. 



The Jejunum and Ileum form the remaining length of the 

 small intestine, and have no external marks of difference from 

 each other. They are strung along the mesentery, and, in con- 

 sequence of their great length, are thrown into folds or convolu- 

 tions, which give to them a complicated appearance. There is, 

 however, no difficulty in tracing them regularly from one end to 

 the other. They occupy the umbilical, the hypogastric, and a 

 part of the iliac regions, and are surrounded by the circuit of 

 the colon. The upper two-fifths is the jejunum, and the lower 

 three-fifths, the ileum. This distinction, originally introduced 

 by Galen,* from a supposition that the jejunum was more fre- 

 quently found empty than any other intestine, has no rigid ana- 

 tomical support. The only difference between the two is, that 

 the valvulse conniventes, abundant in the whole length of the je- 

 junum, become less so at the upper part of the ileum, and finally 

 disappear entirely towards its lower extremity. The distinction 

 has, therefore, been rejected by the most approved modern au- 

 thorities, such as Haller, Soernmering, Meckel, and so on. 



It sometimes happens, that the intestinum tenue has one or 

 more blind pouches appended to its sides and opening into its 

 cavity. 



The small intestine is supplied with blood from the superior 

 mesenteria artery. Its nerves come from the sympathetic. 



The Mesentery (Mesenterium) is a process of peritoneum 

 which serves, as mentioned, to connect the intestinum tenue to 

 the posterior parietes of the abdomen, and extends its connex- 

 ions from the left side of the second lumbar vertebra to the right 

 iliac fossa. This attachment, called the root, is about six inches 

 in length; whereas its lower circumference, which encloses the 



* Portal, Anat. Med. 



