PERITONEUM. 173 



colon ; it crosses the abdomen at its upper part, under the 

 name of the transverse colon, descends upon the left side, 

 as the descending colon, covering in the left kidney, to the 

 left inguinal region, where it forms several folds, called the 

 sigmoid flexure, and then dipping into the pelvis behind 

 the bladder becomes the rectum. 



All the viscera, so far as they can be seen, as well as the 

 walls of the abdomen, will be found covered with a thin, 

 shining membrane, called the peritoneum ; this facilitates 

 the movements of the various organs, which are by no 

 cans inconsiderable, the position of the body influencing 

 ery greatly the position of the viscera. They have, not- 

 withstanding, been located in regions, and though the 

 l)ou ndaries are merely arbitrary, and are indicated only in 

 the most general way as including the organs within their 

 limits, allusion is constantly made to them. 



It will be found convenient to indicate these regions by strings, 

 which should be stretched in the directions about to be enumerated, 

 viz. : two vertical lines, each from the most dependent portions of the 

 cartilages of the eighth ribs to tbe centre of Poupart's ligament ; a 

 transverse line corresponding to the summits of the ilia, and another 

 to the most dependent portion of the ribs. 



We thus have three zones, each subdivided into three 

 regions. The three in the upper zone are, lateralty, the 

 right and left hypochondriac, in the centre, the epigastric. 

 In the middle zone, laterally, the right and left lumbar, and 

 in the centre the umbilical. In the lower zone, laterally, 

 the right and left inguinal, and in the centre the hypogas- 

 t/'ic. By handling the abdominal contents, the student can 

 satisfy himself that the right hypochondriac region con- 

 tains the liver, the left the spleen, and part of the stomach, 

 while the epigastric contains a part of both the stomach 

 and the liver; the lumbar regions contain the kidneys on 

 either side ; the umbilical the small intestines ; the right 

 inguinal region contains the caecum, the left the sigmoid 

 flexure ; the hypogastric region contains the bladder and 

 rectum, and in the female, the uterus. 



PERITONEUM. 



The PERITONEUM is a serous membrane. Considered in 

 its simplest form, a serous membrane is a hollow sac, into 

 which a viscus protrudes itself, and thus, while getting a 

 covering itself, lies within another covering of the same 



15* 



