ABDOMINAL VISCERA. 



THE ABDOMEN. 



THE abdomen is the largest cavity in the body. It 

 is limited above by the diaphragm, below by the upper 

 plane of the true pelvis. It is ovoidal in shape, and is 

 bounded behind by the spine, psoas and quadratus 

 muscles ; anteriorly and at the sides, by the ribs, ab- 

 dominal muscles, and the iliac bones. It is lined by a 

 serous membrane, the peritoneum, which is also re- 



FIG. 161. THE ABDOMEN-. 



(The dotted lines represent the planes that divide the abdomen into nine regions.) 



fleeted around the abdominal viscera, and serves to keep 

 them in place. There are six openings into the abdomi- 

 nal cavity, namely, the aortic; cesophageal; the opening 

 for the vena cava ; in the foetus, the umbilicus ; and below, 

 the openings of the inguinal canals. Normally, these are 

 sufficiently strong to resist the hernia of the abdominal 

 viscera. The abdominal cavity is divided into nine regions 



(367) 



