ioo LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



cavity, is exposed. Its anterior wall is formed by the concavely arched diaphragm 

 which completely separates the peritoneal from the pleural cavities. Posterior 

 to the diaphragm and shaped so as to fit the concave surface of the diaphragm 

 is the large, lobed liver, generally grayish brown in preserved specimens. Pos- 

 terior to the liver the peritoneal cavity is filled by the coils of the intestine. In 

 the cat the intestine is covered ventrally by a thin membrane impregnated with 

 streaks of fat, the greater omentum. This membrane is present also in the rabbit, 

 but is very much smaller and less conspicuous. At the posterior end of the per- 

 itoneal cavity may be noted the pear-shaped urinary bladder, generally distended 

 with fluid. On raising the liver and looking dorsally and to the left of it will be 

 found the stomach with the spleen attached to its left border. On the dorsal wall 

 of the peritoneal cavity at about the level of the posterior ends of the liver lobes 

 are the kidneys, round organs; to see them, gently lift the coils of the intestine. 

 In female specimens, especially those which are pregnant, the horns of the uterus 

 will be noted as a tube on each side in the posterior part of the peritoneal cavity. 



The peritoneal cavity is lined by a membrane, the peritoneum. As in all 

 coelomate animals, that portion of the membrane on the inside of the body wall 

 is the parietal peritoneum. In both dorsal and ventral regions the peritoneum 

 is deflected from the body wall and passes over the surface of the viscera, forming 

 a covering layer, the visceral peritoneum or serosa, for all of the viscera. In 

 passing to and from the body wall to the viscera, the peritoneum forms double- 

 walled membranes, the mesenteries or ligaments. The dorsal mesentery is present 

 intact in mammals, and the ventral mesentery persists in the region of the liver 

 and urinary bladder as in other vertebrates. 



Examine the stomach first, by raising the liver and pressing it craniad. The 

 exposure of the stomach is facilitated by slitting the diaphragm on the left side. 

 The stomach is a large and rounded organ in the rabbit, smaller and more elongated 

 in the cat. Find where the esophagus emerges from the diaphragm and enters 

 the anterior surface of the stomach. The area of junction of the stomach and 

 esophagus is called the cardia; and the region of the stomach adjacent to the junc- 

 tion, the cardiac end of the stomach. The shorter, slightly concave anterior 

 surface of the stomach from the cardia to the pylorus is the lesser curvature; the 

 larger convex posterior surface, the greater curvature. The saclike bulge of 

 the stomach to the left of the cardia is known as the fundus; the remainder 

 of the stomach, the body. At the right the stomach passes into the small 

 intestine, the point of junction, known as the pylorus, being marked by a con- 

 striction, beyond which the small intestine makes an abrupt bend. Along the left 

 side of the stomach lies the spleen, a rather large organ in the cat, but smaller in 

 the rabbit. 



The relations of the stomach to the peritoneum are somewhat complicated. 

 Raise the fundus and note the mesogaster extending from the dorsal wall to the 

 stomach. Only a small portion of the mesogaster passes directly to the stomach; 



