THE ABDOMINAL WALLS 255 



The weakest part of the posterior wall of the canal (the 

 abdominal inguinal ring) is placed opposite the strongest part 

 of the anterior wall ; similarly, the weakest part of the anterior 

 wall (the subcutaneous inguinal ring) is 'placed opposite the 

 strongest part of the posterior wall (Fig. 77). 



The Floor of the canal is formed by the upper surface of the 

 inguinal ligament and, at its medial end, by the lacunar ligament 

 (of Gimbernat). 



The inferior (deep) epigastric artery arises from the external 

 iliac as it lies in the extra-peritoneal fat below the abdominal 

 inguinal (int. abd.) ring. At first the vessel lies below the ring, 

 but it bends upwards and medially along its medial border. 

 This relationship is of importance in connection with the 

 operation for strangulated inguinal hernia, and is referred to 

 again on p. 263. 



Coverings of the Testis and Spermatic Cord. In its 

 descent (p. 257) from the abdomen to the scrotum, the testis 

 traverses the inguinal canal. As it pushes its way through the 

 transversalis fascia at the abdominal inguinal ring, it gains for 

 itself and the spermatic cord a sheath of this fascia. This 

 covering is known as the internal spermatic or infundibuliform 

 fascia. The testis next passes under cover of the lower border 

 of the internal oblique, and as it does so, it drags down some 

 fibres of the muscle to form the cremaster. In the child, these 

 fibres can be traced from the inguinal ligament and the lower 

 border of the internal oblique down the anterior surface of the 

 cord and up its posterior surface to the pubic tubercle (spine). 

 Some extend to the testis, while others only pass downwards for 

 a short distance on the cord before looping upwards again. 

 This covering lies outside the internal spermatic fascia and is 

 known as the cremasteric muscle and fascia. The contraction of 

 the muscular fibres can draw the testis from the scrotum up to 

 the subcutaneous inguinal ring. 



On passing through the external oblique aponeurosis at the 

 subcutaneous inguinal ring, the testis gains a third covering, 

 the external spermatic fascia. 



From the above it will be seen that the testis and that part 

 of the spermatic cord which lies outside the inguinal canal have 

 three coverings. In the medial part of the canal the spermatic 

 cord has two coverings, and in the lateral part only one, the 

 internal spermatic fascia. 



The Spermatic Cord can be examined in the upper part of 



