ABDOMINAL WALL 403 



The floor is formed, in the first part of the canal, by the 

 upper grooved surface of the inguinal ligament. Towards the 

 outlet, however, the floor becomes broader and more definite ; 

 here it is formed not only by the inguinal ligament, but also by 

 the lacunar ligament. At this point, as the student has 

 already observed, the cord rests directly upon the abdominal 

 surface of the latter ligament. The parts which enter into 

 the formation of the anterior wall are (i) the aponeurosis of 

 the external oblique throughout the entire extent of the canal ; 

 and (2) the lower border of the internal oblique in the lateral 

 third of the canal. These facts can be readily verified by 

 restoring the structures to their original positions. The parts 

 which compose the posterior wall are still in situ. Naming 

 them in order, from the inlet to the outlet, they are (i) the 

 fascia transversalis ; (2) the falx inguinalis ; and (3) the 

 ligamentum inguinale reflexum, when it is strongly developed. 



But it may be asked, does the transversus abdominis muscle 

 take no part in the formation of the inguinal canal ? The 

 student can readily satisfy himself as to this point. He will 

 notice that the arched lower border of this muscle does not 

 descend so low as that of the internal oblique, that, in fact, 

 it stops short immediately above the abdominal inguinal ring. 

 The canal is closed superiorly by the approximation of the 

 anterior and posterior walls above the cord and by the inter- 

 vention between these walls of the lower border of the trans- 

 versus abdominis. 



There is still another point to be noted, viz. the relation 

 which the inferior epigastric artery bears to the posterior wall 

 of the canal. This vessel can be felt (and, indeed, in most 

 cases seen) extending obliquely upwards and medially, 

 posterior to the transversalis fascia, to the lateral border of the 

 rectus. A triangular space is thus mapped out by the artery, 

 the inguinal ligament, and the lateral border of the rectus. 

 This receives the name of the triangle of Hesselbach. The 

 space corresponds with the posterior wall of the inguinal canal, 

 and chiefly with that part of it which is composed of the falx 

 inguinalis (O.T. conjoined tendon). 



In the female the inguinal canal is much smaller than in 

 the male. It has the same boundaries, and it is traversed 

 by the round ligament of the uterus. 



Arteries of the Abdominal Wall. The following arteries 

 will be found in the abdominal wall : 



