The Intestines. 189 



attachments of the mesenteries, in which the chief plexuses and 



related ganglia of the sympathetic system will afterwards be traced. 



(For the general relations of the intestines and mesenteries, see pp. 82, 99.) 



1. Beginning at the pylorus, trace the course of the small 

 intestine, as follows: Its first portion, the duodenum, forms a 

 U-shaped loop lying on the dorsal wall of the abdominal cavity 

 to the right of the vertebral column. The distal end of this loop, 

 when traced from the right side, disappears in the peritoneum and 

 may then be picked up in a forward position on the left side of the 

 mass. This point marks the beginning of the second portion, the 

 mesenterial small intestine (intestinum tenue mesenteriale), 

 which may be traced to its termination on the greatly enlarged 

 caecum. The connection with the caecum is through a rounded 

 semi-expanded sac, the sacculus rotundus. The terminal 

 portion of the small intestine is somewhat more difficult to follow 

 on account of the adhesions of its peritoneum with that of the large 

 intestine. 



2. Examine the divisions of the duodenal loop and related 

 structures, as follows: 



(a) The superior, descending, transverse (horizontal), and 

 ascending portions of the duodenal loop. 



(b) The common bile duct, opening on the dorsal wall of the 

 /sy^ superior portion. 



(c) The mesoduodenum, a fold of peritoneum joining the 

 various parts of the loop. 



(d) The pancreas (Fig. 3 B, p. 22). Its principal portion is 

 here seen as a diffuse brownish mass lying in the mesoduo- 

 denum. Its duct (d. pancreatis) opens into the posterior 

 portion of the ascending limb. 



(e) The superior pancreaticoduodenal artery, a branch of 

 the gastroduodenal (see p. 185), passes backward on the first 



• portion of the descending limb. 



(f) The inferior pancreaticoduodenal artery (a. pancreatico- 

 duodenalis inferior), a branch of the superior mesenteric 

 (p. 192), enters the mesoduodenum from the left side and 

 supplies the major portion of the loop. An anterior branch 

 anastomoses with (e). 



