THE PERITONEUM. 727 



upon itself to the transverse colon, forms the internal layer of the great otnen- 

 tum; it covers the upper surface of the transverse colon, and, passing backwards 

 to the spine, forms the upper layer of the transverse meso-colon. Ascending in 

 front of the pancreas and crura of the Diaphragm, it lines the back part of the 

 under surface of that muscle, from which it is reflected on to the posterior bor- 

 der of the liver, forming the inferior layer of the coronary ligament. From 

 the under surface of the liver it may be traced to the transverse fissure, where 

 it is continuous with the posterior layer of the lesser omentum, the point 

 whence its reflection was originally traced. 



The space included in the reflections of this layer of the peritoneum is called 

 the lesser cavity of the peritoneum, or cavity of the great omentum. It is bounded, 

 in front, by the lesser omentum, the stomach, and the descending part of the 

 great omentum; behind, by the ascending part of the great omentum, the trans- 

 verse colon, transverse meso-colon, and its ascending layer; above, by the liver; 

 and below, by the folding of the great omentum. This space communicates 

 with the general peritoneal cavity through the foramen of Winslow, which is 

 situated behind the right, or free border of the lesser omentum. 



The foramen of Winslow is bounded in front by the lesser omentum, inclosing 

 the vena portas and the hepatic artery and duct; behind, by the inferior vena 

 cava; above, by the lobulus Spigelii; below, by the hepatic artery curving for- 

 wards from the caeliac axis. 



This foramen is nothing more than a constriction of the general peritoneal 

 cavity at this point, caused by the hepatic and gastric arteries passing forwards 

 from the caeliac axis to reach their respective viscera. 



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

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

 the transverse colon, sigmoid flexure, upper end of the rectum, the uterus, and 

 ovaries. 



The viscera only partially invested by peritoneum are the descending and 

 transverse portions of the duodenum, the cascum, the ascending and descending 

 colon, the middle portion of the rectum, and the upper part of the vagina and 

 posterior wall of the bladder. The kidneys, suprarenal capsules, and pancreas 

 are covered by the membrane without receiving any special investment from it. 



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

 bladder, the whole of the front, and the lower part of the posterior wall of the 

 vagina, have no peritoneal covering. 



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 

 ligaments, 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 the stomach 

 to certain viscera in its neighborhood. 



The Ligaments, formed by folds of the peritoneum, include those of the liver, 

 spleen, bladder, and uterus. They will be found described with their respective 

 organs. 



The Omenta are the lesser omentum, the great omentum, and the gastro- 

 splenic omentum. 



The fesser omentum (g astro -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 oesophagus; but at ehe 

 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 comrnu- 

 nis choledochus, the portal vein, lymphatics, and the hepatic plexus of nerves 

 all these structures being inclosed in loose areolar tissue, called Glisson's capsule. 



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



