386 



OPERATIONS OX THi: DIGESTIVE APPARATUS. 



contents. In one place muscnlo-carfcilag-inous, or bony, it is in 

 another, musculo-aponeurotic. In some parts protected by only a 

 single layer of muscle, as in its anterior wall ; in others the layers 

 of muscular aponeurotic structure, or of fibrous bandages, are re- 

 inforced by a powerful elastic band, as in the inferior portion, by 

 the tunica abdominalis. But besides this variety in the elements 



Fig. 372.— Muscles of the Inferior Abdominal Region. 



1, aponeurosis of the great oblique; 2, fleshy portion ol the small oblique; 3, straight of 

 the abdomen; 3', transverse of the abdomen; 4, pre-pubic tendon; 5, inguinal ring; 6, its 

 anterior border; 7, the posterior; 8, external commissure; 9, internal commissure; 

 10, posterior border of the aponeurosis of the great oblique ; 11, internal crural aponeu- 

 rosis; 1'^, flap of the aponeurosis of the great oblique, drawn downward to show th'^^ 

 origin of the reflex portion which forms the crural arch ; 14, remains of the umbilicus. 



forming the walls of the cavity, there is also to be taken into con- 

 sideration the fact that, at certain points in the walls, natural 

 openings exist, and that the abdominal cavity is therefore not 

 strictly a close cavity. These passages consist of the inguino-cru- 

 ral openings, the umbihcus and those found in the diaphragm for 



