71 6 A MANUAL OF ANATOMY 



reflected over the left lateral and left half of the anterior wall of 

 the abdomen as far as the middle line. 



The relations of the peritoneum to the duodenum, pancreas, and 

 kidneys will be described when these viscera fall to be considered. 



Omenta. — ^The great or gastro-colic omentum (epiploon) extends 

 from the great curvature of the stomach and first inch of the first 

 part of the duodenum to the transverse colon, descending in its 

 course usually as low as the pelvic brim, and lower on the left 

 side than on the right, which accounts for the greater frequency 

 of an omental hernia on the left side. It covers the coils of the 

 jejunum and ileum. At the great curvature of the stomach it 

 contains between its two layers the right and left gastro-epiploic 

 arteries, and the epiploic branches of these vessels, which are long 

 and slender, descend into it. The great omentum is often of small 

 size, thus leaving many of the coils of the small intestine uncovered, 

 or it may even be displaced into the left hypochondrium. It is 

 composed of four layers of peritoneum, two of which descend from 

 the great curvature of the stomach, inseparably united, to the 

 region of the pelvic brim, these being called the anterior or descend- 

 ing layers. The other two layers, also inseparably united, ascend 

 from the region of the pelvic brim to the transverse colon, these 

 being called the posterior or ascending layers. Between the two 

 anterior and the two posterior layers there is usually, in healthy 

 persons, a space which represents a part of the small cavity of the 

 peritoneum, and is known as the bag or sac of the great omentum. 

 In many cases, however, this space is scarcely demonstrable on 

 account of adhesions. It is most conspicuous a little below the 

 great curvature of the stomach. 



The small or gastro-hepatie omentum extends from the small 

 curvature of the stomach and first inch of the first part of the 

 duodenum to the portal fissure of the liver, and also to the venosal 

 fissure. It is composed of two layers of peritoneum which, at the 

 small curvature of the stomach, contain between them the anterior 

 and posterior branches of the gastric and pyloric arteries. For 

 the most part its two layers are inseparably united, but at its 

 right border, which is free, it contains between them the following 

 structures : (i) the common bile-duct to the right side ; (2) the 

 hepatic artery, invested by the hepatic plexus of sympathetic 

 nerves, to the left side ; (3) the vena portae, which lies between 

 these two, and on a plane posterior to both ; and (4) lymphatic 

 vessels. This right or free border, with the foregoing contents, 

 lies in front of the foramen of Winslow. The left border of the 

 gastro-hepatie omentum is short on account of the oblique position 

 of the stomach, and is attached to the diaphragm between the 

 caval and oesophageal openings. The anterior layer of the small 

 omentum is formed by peritoneum belonging to the great sac, and 

 the posterior layer by that belonging to the small sac, these two layers 

 becoming continuous with each other round the right or free border 

 of the omental fold in front of the foramen of Winslow, 



