THE BODY CAVITY. 219 
suspends the organ from the body wall. Between the layers 
of each inesentery 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 
