3 86 APPLIED ANATOMY. 



inserts into the crest and anterior surface of the body of the pubis. The fibres run- 

 ning across from one column to the other are the intercolumnar fibres (fibrte inter- 

 cruralis^) and are prolonged over the cord as the intercolumnar fascia (Fig. 395). 



The internal ring {annulus inguinalis abdominalis} is the opening in the 

 transversalis fascia where the cord enters the canal. It is 1.25 to 2 cm. (^ to ^ in.) 

 above the middle of Poupart's ligament. This brings it to the outer side of the 

 external iliac artery. 



The body being upright, the inguinal canal has an anterior and a posterior wall 

 and a roof and floor. The anterior wall (nearest to the skin) is formed by the 

 aponeurosis of the external oblique, and by the internal oblique muscle for its outer 

 third and sometimes even its outer half. The posterior wall is nearest to the verte- 

 bral column. It is formed by- the transversalis fascia and at its inner third the con- 



Internal oblique 



Blending of the layers 

 with the sac 



Spermatic cord 



Transversalis 



Cut edge of internal 

 oblique 



Hernial sac 

 Intestine 



Omentum 



Tunica vaginalis 

 Testicle 



FIG. 397. The coverings of an acquired oblique inguinal hernia; from an actual dissection. The external and 

 internal oblique have been divided along Poupart s ligament and turned inward exposing the transversalis. 



joined tendon. The roof, nearest to the head, is formed by the arching fibres of the 

 internal oblique muscle and still farther above the transversalis. The floor is 

 nearest to the feet. The cord rests on Poupart's ligament with some of the fibres of 

 the cremaster muscle. 



To the inner side of the internal ring and almost midway between it and the 

 external ring runs the deep epigastric artery, it is between the transversalis fascia and 

 peritoneum, in the subperitoneal fat. 



Coverings of an Indirect or Oblique Hernia. As the intestine descends 

 to form an oblique inguinal hernia it pushes in front of it the following structures : 

 peritoneum, subperitoneal fat, transversalis (infundibuliform) fascia, internal oblique 

 muscle (cremaster), external oblique aponeurosis (intercolumnar fascia), subcuta- 

 neous tissue, and skin. These structures are therefore cut in opening the sac to 

 expose the intestine. The hernia always descends in front of the cord and testicle, 

 hence these are posterior. The site of strangulation may be either at the external 

 ring as the hernia passes through the external oblique muscle or at th * internal ring 



