CHAPTER XVIII. 

 ABDOMEN. 



ABDOMINAL PARIETES. MUSCLES AND THEIR 

 REGIONS. ACTIONS. 



STRUCTURES FORMING APONEUROSES. 



ANTERO- LATERAL NERVES, &c. 



WALLS. LINEA ALBA. 



SUPERFICIAL FASCIA. UMBILICUS. 



The abdomen is the largest serous cavity of the body, 

 and, when viewed from in . front, its anterior surface is 

 seen to be of a somewhat hexagonal shape; the upper 

 limit being the converging thoracic margins ; the lower 

 limit, Poupart's ligament, while the sides are represented 

 by the edges of the lateral boundaries. The abdominal 

 cavity is bounded above, by the under surface of the dia- 

 phragm ; below, by the brim of the true pelvis ; behind, by 

 the diaphragm, the quadratus lumborum and psoas mus- 

 cles, the lumbar fascia, the vertebral column and the pos- 

 terior portions of the ilia; laterally, by the expanded ilia 

 and the postero-lateral portions of the external oblique, 

 the internal oblique, and the transversalis muscles ; while 

 in front, are these muscles with their aponeuroses and, in 

 addition, the recti and the pyramidales muscles. 



Regions of the Abdomen. The abdomen may be 

 divided, for the sake of convenience of description in nor- 

 mal or in pathological conditions, into nine regions, by 

 means of two vertical and two horizontal lines. There 

 have been a number of different markings proposed by 

 anatomical writers for these divisional lines, but perhaps 

 the best, for the horizontal lines, are : For the upper plane, 

 a line joining the eleventh rib on either side and passing 

 through the second lumbar vertebra ; for the lower plane, 

 one joining the anterior superior iliac spines and passing 



