280 SURGICAL APPLIED ANATOMY. [Chap. xvi. 



epigastric artery, an internal between the urachus 

 and the hypogastric artery, and a middle between the 

 tract of the latter vessel and the epigastric trunk. 

 The internal ring (so called) is just to the outer side 

 of the epigastric artery, and the site of the summit of 

 the inguinal canal is indicated by a depression in the 

 peritoneum. When a hernia follows the inguinal 

 canal throughout its entire length, it is called oblique, 

 indirect, or external; " oblique" or "indirect" from 

 its taking the oblique direction of the canal, "external" 

 from the position of its neck with reference to the 

 epigastric vessel. The coverings of such a hernia 

 would be the same as those of the cord, viz., the skin, 

 the superficial, intercolumnar, cremasteric and infundi- 

 buliform layers of fascia, the subserous tissue, and 

 the peritoneum. When the hernia escapes to the 

 inner side of the deep epigastric artery, through the 

 space known as Hesselbach's triangle, it is called a 

 direct or internal hernia for reasons that will be 

 obvious. There may be two forms of direct hernia. In 

 one form the gut escapes through the middle fossa 

 above described, in the other through the inner fossa 

 between the hypogastric artery and the outer edge of 

 the rectus muscle, The middle fossa is nearly oppo- 

 site to the summit of the external ring. A hernia 

 escaping through that fossa would enter the inguinal 

 canal some little way below the point of entrance of 

 an oblique hernia, and would have the same coverings 

 as that hernia, with the exception of the infundibuli- 

 form fascia. The first covering, indeed, that it would 

 receive from the canal structures would be the cre- 

 masteric fascia. The inner fossa corresponds, so far 

 as the inguinal canal is concerned, with the external 

 ring. A hernia escaping through this fossa would be 

 resisted by the conjoined tendon and the triangular 

 ligament. These structures are either stretched over 

 the hernia so as to form one of its coverings, or the 



