124 ELEMENTS OF MAMMALIAN ANATOMY. 



close along the concavity of the duodenum. It has two 

 ducts, one of which enters the duodenum in common with 

 the common bile duct, while the other enters about three 

 centimeters further caudad. The pancreatic juice acts on 

 the starches, proteids, and fats. 



THE PERITONEUM. 



The peritoneum (Fig. 61) is the serous sac lining the 

 abdominal cavity and investing most of the organs therein 

 contained. The four portions of the peritoneum are known 

 as the omenta, the mesenteries, parietes, and ligaments. 



The omenta are three in number, the largest of which is 

 the great or gastrocolic omentwn, stretching caudad from 

 the dorsal abdominal wall and the greater curvature of the 

 stomach, so as to cover the intestine like an apron. It is 

 composed of four layers of peritoneum forming a closed 

 sac, and bearing more or less fat. Two layers form the 

 ventral wall of the sac attached to the stomach, and two 

 layers are also present in the dorsal wall of the sac which 

 invests the pancreas. 



The lesser omentum, or gastrohepatic amentum, extends 

 caudad from the liver to the pyloric part of the stomach 

 and duodenum. Its two folds extend from the two sides 

 of the portal fissure, ensheathing the portal vein, hepatic 

 artery, and cystic duct. The gastrosplenic omen-turn stretches 

 from the cardiac region of the stomach to the spleen, which 

 it embraces, and then proceeds to the diaphragm. 



The mesenteries are the two layers of peritoneum 

 suspending the intestine from the dorsal abdominal wall. 

 There are four mesenteries : the true mesentery, suspending 

 the jejunum and ileum ; the mesoduodenum, suspending the 

 duodenum; the mesocolon, suspending the colon; and the 

 mesorectum, suspending the rectum. 



The parietes or parietal peritoneum is that portion lining 



