THE ABDOMEN 



1241 



addition to this, the abdomen varies in form and extent with age and sex (Fig. 

 957). In the adult male, with moderate distention of the viscera, it is oval or 

 barrel-shaped, but at the same time flattened from before backward. In the 

 adult female, with a fully developed pelvis, it is conical with the apex above, and 

 in young children it is conical with the apex below. 



Lower hmg 

 limit 



Lower pleural _ 

 limit 



Diaphragm 



-.- Heart contour 



Stomach 



Peritoneum 



. Small intestine 



Xigmoid 

 flexure 



1 Bladder 



Fi<;. 958. Topography of thoracic and abdominal viscera. 



Boundaries. The boundary between the thorax and abdomen is the Dia- 

 phragm, which extends as a dome over the abdomen, so that the cavity extends 

 high into the bony thorax, reaching on the right side, in the midclavicular line, 

 to the upper border of the fifth rib; on the left side it falls below this level by 

 about half an inch or more. The abdomen proper is bounded in front and at the 

 sides by the lower ribs, the abdominal muscles, and the iliac fossas; behind, by the 

 vertebral column and the Psoas and Quadratus lumborum muscles; above, by the 

 Diaphragm ; below, by the plane of the inlet or brim of the pelvis. The muscles 

 forming the boundaries of the cavity are lined upon their inner surface by a layer 

 of fascia, differently named, according to the part which it covers. 



