662 ORGANS OF DIGESTION. 



The viscera thus shown to be almost entirely invested by peritoneum are the 

 liver, stomach, spleen, first portion of duodenum, jejunum, and ileum, transverse 

 colon, sigmoid flexure, upper end of rectum, uterus, and ovaries. 



Those viscera partially covered by it are the descending and transverse portions 

 of the duodenum, the caecum, the ascending and descending colon, the middle por- 

 tion of the rectum, and the upper part of the vagina and posterior wall of the blad- 

 der. The kidneys, supra-renal capsules, and pancreas, are covered by this mem- 

 brane without receiving any special investment from it. 



The lower end of the rectum, the neck, base, and anterior surface of the bladder, 

 and the lower part of the vagina, have no peritoneal investment. 



Numerous folds are formed by the peritoneum, extending between the various 

 organs. These serve to hold them in position, and, at the same time inclose the 

 vessels and nerves proceeding to each part. Some of the folds are called liga- 

 ments, from their serving to support the organs in position. Others, which 

 connect certain parts of the intestine with the abdominal wall, constitute the 

 mesenteries; and, lastly, those are called omenta, which proceed from one viscus to 

 another. 



The LIGAMENTS, formed by folds of the peritoneum, include those of the li ver, 

 spleen, bladder, and uterus. They are described with their respective organs. 



The OMENTA are the lesser or gastro-hepatic omentum, the great or gastro-colic 

 omentum, and the gastro- splenic omentum. 



The lesser omentum (gastro-hepatic} is the duplicature which extends between 

 the transverse fissure of the liver, and the lesser curvature of the stomach. It is 

 extremely thin, and consists, as before said, of two layers of peritoneum. At the 

 left border, its two layers pass on to the end of the oasophagus ; but, at the right 

 border, where it is free, they are continuous, and form a free rounded margin, 

 which contains between its layers the hepatic artery, the ductus communis chole- 

 dochus, the portal vein, lymphatics, and hepatic plexus of nerves ; all these struc- 

 tures being inclosed in loose areolar tissue, called Glissoii's capsule. 



The great omentum (gastro-colic) is the largest peritoneal fold. It consists of 

 four layers of peritoneum, two of which descend from the stomach, one from its 

 anterior, the other from its posterior surface ; these, uniting at its lower border, 

 descend in front of the small intestines, as low down as the pelvis ; and the same 

 two ascend again as far as the transverse colon, where they separate and inclose 

 that part of the intestine. These separate layers may be easily demonstrated in 

 the young subject ; but in the adult, they are more or less inseparably blended. 

 The left border of the great omentum is continuous with the gastro-splenic omen- 

 tum ; its right border extends as far only as the duodenum. The great omentum 

 is usually thin, presents a cribriform appearance, and always contains some adipose 

 tissue, which, in fat subjects, accumulates in considerable quantity. Its use ap- 

 pears to be to protect the intestines from cold, and to facilitate their movement 

 upon each other during their vermicular action. 



The gastro-splenic omentum is the fold which connects the concave surface of 

 the spleen to the cul-de-sac of the stomach, being continuous by its lower border 

 with the great omentum. It contains the splenic vessels and the vasa brevia. 



The MESENTERIES are the mesentery proper, the mesocsecum, the ascending, 

 transverse, and descending mesocolon, the sigmoid mesocolon, and the meso- 

 rectum. 



The mesentery (ntom>, rtpo), so called from being connected to the middle 

 of the cylinder of the small intestine, is the broad fold of peritoneum which 

 connects the convolutions of the jejunum and ileum with the posterior wall of the 

 abdomen. Its root, the part connected with the vertebral column, is narrow, 

 about six inches in length, and directed obliquely from the left side of the second 

 lumbar vertebra, to the right sacro-iliac symphysis. Its intestinal border is much 

 longer ; and here its two layers separate, so as to inclose the intestine, and form 

 its peritoneal coat. Its breadth, between its vertebral and intestinal border, is 

 about four inches. Its upper border is continuous with the under surface of the 



