524 



HUMAN ANATOMY. 



As a result of these processes the lower portion of the abdominal wall is 

 traversed on either side by the spermatic cord or by the ligamentum teres of the 

 uterus, and it is customary to regard the space occupied by the one or the other of 

 these structures as a canal, which is termed the inguinal canal. It should be 

 understood, however, that an actual space surrounding the cord or ligament does 

 not exist, the walls of the canal being united to the structure contained within it. 

 Nevertheless, the union is by no means a strong one, the region of the abdominal 

 ■wall traversed by the ligamentum teres or especially by the spermatic cord being 

 relatively weak and not infrequently the seat of an inguinal hernia. 



The inguinal canal is somewhat over 3 cm. {i)4 in. ) in length and is situated 

 immediately above Poupart's ligament, which it crosses obliquely from above down- 

 ward, medially, and forward. Its upper or inner end is about midway between the 

 anterior superior spine of the ilium and the spine of the pubis, and lies about 12 mm. 

 (^2 in.) above the line of Poupart's ligament. It is marked by a more or less distinct 

 depression on the posterior surface of the abdominal wall surrounding the spernrjatic 

 cord or round ligament, termed the internal abdominal ring (annulus inguinalis 



Fig. 530. 



-;*--<;iSi 



Anterior superior iliac spine 



Poupart's ligament 



Falciform process 



Iliac portion of fascia lata 



Sapfienous opening 



Femoral artery 

 Femoral vein 



Aponeurosis of external oblique 



Intercolumnar fibres 



External abdominal ring 

 External pillar 

 Internal pillar 



Internal saphenous vein 



Ginibernat's ligament, inner 

 boundary of femoral ring 



Pubic portion of fascia lata 

 Spermatic cord 



Dissection of right inguinal region, showing external abdominal rmg and saphenous opening. 



abdominis). The depression (Fig. 532) is due to the transversalis fascia being pro- 

 longed downward over the spermatic cord as a funnel-like sheath, the infiindibidi- 

 form fascia. The lower or medial end of the canal corresponds to the external 

 abdominal ring (annulus inguinalis subcutaneus) (Figs. 523, 530), and lies just 

 lateral to and a little above the spine of the pubis and is surrounded by the lower 

 medial portion of the aponeurosis of the external oblique. The fibres of the aponeu- 

 rosis which bound this ring are somewhat thickened, forming what are termed the 

 pillars (crura) of the ring, the uppermost of which, the iiitcrnal pillar (crus superior), 

 consists of fibres passing to the symphysis pubis ; the lower one, the external pillar 

 (crus inferior), is formed by the fibres passing to the pubic spine, and corresponds 

 to the medial end of Poupart's ligament. Stretching across between the two crura 

 are numerous obliquely arching intercolumnar fibres (fibrae intercrurales) which extend 

 laterally almost as far out as the anterior superior spine of the ilium. From the 

 margins of the external ring an attenuated prolongation of the aponeurosis of the 

 external oblique is continued downward over the spermatic cord as a thin membrane 

 known as the intercolumnar or external spermatic fascia. 



