REFLECTIONS OF PERITONEUM, 307 



somewhat nearer their inner than their outer borders, and the 

 transpyloric plane crosses them transversely, a third of the right 

 kidney being above this plane and two-thirds below, whilst two-fifths 

 of the left kidney lie above the plane and three- fifths below. 



They are situated at the back of the abdomen, opposite the last Position : 

 dorsal and upper two or three lumbar vertebrae, and occupy parts 

 of the epigastric, hypochondriac, umbilical, and lumbar regions. 

 Their position is somewhat oblique, the upper end being nearer to 

 the spine than the lower ; and the surface which is called anterior 

 looks much outwards. 



They lie behind the peritoneum, and are surrounded with fat. relations 

 They rest upon the diaphragm, the psoas and quadratus lumborum 5^) ' 

 muscles. The upper end supports the suprarenal body ; and at the 

 inner border the vessels enter, and the duct (ureter) leaves the organ. 



The differences on the two sides will be pointed out later on 

 (pp. 353 et *>:<!). 



The relations of the pancreas must be omitted for the present, but Pancreas 

 they will be found on pp. 329 and 330. 



THE PERITONEUM. 



This is the largest serous membrane in the body. In the male it Perito- 

 is a closed sac, like other serous membranes ; but in the female there 

 is an aperture of communication with the Fallopian tube, and the arrange- 

 mucous lining of the latter becomes continuous with the serous mi 

 membrane. It lines the wall of the abdomen (parietal peritoneum), 

 and is reflected over the several viscera (visceral peritoneum), some 

 of which it invests completely, except where the vessels enter. The surfaces ; 

 inner surface is free and smooth ; but the outer is rough, when it is 

 detached from the parts to which it is naturally adherent. The 

 membrane as it passes from viscus to viscus, or from the abdominal 

 wall to viscera, forms processes or folds, to which different names are folds, 

 given, and which for the most part consist of two layers enclosing 

 vessels. 



The continuity of the sac may be traced both horizontally and 

 vertically. 



Horizontal circuit round the lou:er part of the abdomen. From the J^JJl^n* 116 

 umbilicus the peritoneum may be followed along the abdominal wall opposite 

 on the left side to the hinder part of the lumbar region, where it <al 

 partly surrounds the descending colon, and thence over the kidney 

 to the front of the spine. Here it is reflected forwards, covering the 

 superior mesenteric vessels, passes round the small intestine, and 

 returns to the spine along the same vessels, thus forming the mesen- 

 tery. From the spine it is continued in the same way on the right 

 side, over the kidney, round the colon, and along the wall of the 

 abdomen to the umbilicus again. 



Vertical circuit (fig. 114). Starting at the under-surface of the Circle from 

 liver, the small omentum (s om) is found descending to the small a 

 curvature of the stomach, where the two layers of which it consists layers, 

 separate to enclose that organ, one passing in front and the other 



x 2 



