THE BODY CAVITY. 219 



suspends the organ from the body wall. Between the layers 

 of each mesentery or ligament blood-vessels may pass to the 

 organs. The third portion or visceral layer covers the organ 

 in question, forming its serous covering. 



The reflections of the peritoneum to form the mesenteries 

 and ligaments may be thus described: 



Caudally the peritoneum covers the whole surface of the 

 bladder and is reflected from its ventral wall to the linea alba 

 as the suspensory ligament of the bladder. Farther craniad 

 the peritoneum suspends the rectum and colon from the mid- 

 dorsal line, forming the mesorectum and mesocolon. The 

 mesocolon continues craniad to the level of the caudal end of 

 the right kidney and is broadest at its cranial end. At this 

 end the mesocolon passes into the mesentery proper, which 

 suspends the small intestine and is very broad and much folded. 

 Its dorsal border is attached to the median line opposite the 

 caudal end of the kidneys and is very short compared to its 

 very long ventral or intestinal border. Toward the cranial end 

 the mesentery of the jejunum passes gradually into the very 

 much shorter duodenal mesentery. This is drawn out at the 

 caudal end of the duodenum into a fold, the duodenorenal liga- 

 ment which attaches the duodenum to the kidney. 



The mesogastrium or peritoneal fold for the stomach passes 

 from that part of the median dorsal line lying between the 

 kidneys and the diaphragm, to the greater curvature of the 

 stomach. It does not pass directly to the stomach, but passes 

 first ventrad of the small intestine as far as the pelvis. Thence 

 it turns craniad to reach the greater curvature of the stomach. 

 The fold thus formed is called the great omentum. It forms 

 the dorsal and ventral walls of a sac, the omental sac, the 

 cavity of which is called the lesser peritoneal cavity. The 

 descending limb of the fold forms the dorsal wall of the sac, 

 and its ascending limb forms the ventral wall. Each of these 

 walls is double like a mesentery, so that the great omentum 

 consists of four sheets of peritoneum. Between the two sheets 

 forming the descending limb lies the left half of the pancreas, 

 which passes thence to the right into the duodenal mesentery. 

 A transverse fold passes from the descending limb of the 



