THE ABDOMEN. 537 



CHAPTER III. 



ACTIVE ORGANS OF THE TRUNK. 



SECOND DIVISION. 

 ORGANS OF THE ABDOMEN. 



THE active organs of the trunk comprise, in the physio- 

 logical order, most of the organs of the abdomen, which are 

 divided into organs of digestion, and organs of absorption. 



GENERAL OBSERVATIONS UPON THE ABDOMEN. 



The abdomen (abdo, to hide) is situated between the 

 chest and pelvis, and is the largest cavity in the body. It 

 is bounded, anteriorly and laterally, by the abdominal 

 muscles and fascia posteriorly by the quadrati lumborum, 

 psoa3 muscles, crura of the diaphragm, and lumbar verte- 

 brae superiorly by the diaphragm, and inferiorly by the 

 pelvis. 



This cavity contains a variety of organs, called viscera, 

 which, for the purpose of localizing them, as well as for 

 the convenience of description, have determined anato- 

 mists to divide the abdomen into regions, (Fig. 166.) 



By drawing two transverse lines across the abdomen, the 

 one superior at the lower margin of the true ribs, the 

 other inferior from the crista of the ilium on the one side 

 to the same point on the opposite then bisecting these at 

 right angles by two vertical lines, one upon either side, and 

 bringing them from the middle of Poupart's ligament to the 

 cartilage of the eighth rib, then taking the anterior circum- 

 ference of the abdomen, we have marked off nine regions. 



Three of these occupy the middle line, and three are 

 upon either side. The superior median region is called the 

 epigastric, the central, the umbilical, the inferior middle,- 

 the hypogastric region. Those upon the sides are the right 

 and left hypochondriac, upon eacli side of the epigastric; 

 the right and left lumbar, upon each side of the umbilical ; 

 and the right and left iliac, upon each side of the hypo- 



