THE ABDOMEN 7' 3 



superior mesenteric vessels. Having surrounded these portions of 

 the small intestine it passes to the posterior abdominal wall upon 

 the other aspect of the superior mesenteric vessels, and so forms the 

 mesentery proper. It then descends over the abdominal aorta and 

 inferior vena cava into the pelvis, where its course will be subse- 

 quently traced. From the apex of the urinary bladder this layer 

 of the peritoneum is reflected on to the posterior surface of the 

 anterior abdominal wall, after lining which it passes to the anterior 

 portion of the under surface of the diaphragm, whence it is reflected 

 on to the postero- superior border of the liver, thus forming the 

 superior layer of the coronary ligament. It then passes over the 

 superior and anterior surfaces of the liver, and, turning round its 

 anterior border, it arrives at the anterior lip of the portal fissure, 

 where it is continuous with the anterior layer of the gastro-hepatic 

 omentum. 



Transverse Course. — The peritoneum may be traced in the 

 transverse direction at two levels, namely, above the trans- 

 verse colon, or at the level of the foramen of Winslow, which is 

 situated behind the right or free border of the gastro-hepatic 

 omentum, and below the transverse colon, or at the level of th^ 

 umbilicus. • 



Above the Transverse Colon, or at the Level of the Foramen of 

 Winslow. — In front of the foramen of Winslow there are the two 

 layers of peritoneum, anterior and posterior, which form the right 

 or free border of the gastro-hepatic omentum, and which contain 

 between them the common bile-duct, the hepatic artery, and the 

 vena portae. Tracing the gastro-hepatic omentum from this point 

 to the left, its two layers separate to enclose the stomach, after whi^h 

 they pass to the gastric surface of the spleen as the gastro-splenic 

 omentum. The two layers of this omentum are anterior and 

 posterior, and they contain between them the vasa brevia of the 

 splenic artery. At the spleen the two layers are immediately in 

 front of the hilum. The anterior layer now takes temporary leave 

 of the posterior layer, and turns completely round the spleen, 

 covering its gastric, ba^al, phrenic, and renal surfaces in succes- 

 sion. On leaving the renal surface of the organ it again passes 

 to the gastric surface, but it is now behind the hilum. Here it 

 meets the posterior layer of the gastro-splenic omentum, which had 

 remained meanwhile stationary immediately in front of the hilum. 

 These two layers now pass backwards to the anterior surface of 

 the left kidney at its upper extremity, and close to its external 

 border, thus forming the lieno-renal ligament. The two layers 

 of this ligament are disposed as right and left, and between them 

 are the splenic branches of the splenic artery. The right layer 

 corresponds with the posterior layer of the gastro-splenic omentum, 

 and the left layer with the anterior layer of that omentum. The 

 right layer of the lieno-renal ligament, after leaving the left kidney, 

 passes to the right over the aorta and inferior vena cava. As it 

 covers the latter vessel it is placed behind the foramen of Winslow, 



