1052 THE SURGICAL ANATOMY OF HERNIA. 



formed between it and the pouch, so that it resembles the congenital form in all 

 respects, except that, instead of enveloping the testicle, that body can be felt 

 below the rupture. 



Direct Inguinal Hernia. 



In direct inguinal hernia the protrusion makes its way through some part of 

 the abdominal wall internal to the epigastric artery. 



At the lower part of the abdominal wall is a triangular space (Hesselbach's 

 triangle), bounded externally by the deep epigastric artery, internally by the 

 margin of the Rectus muscle, below by Poupart's ligament (Fig. 582). The con- 

 joined tendon is stretched across the inner two-thirds of this space, the remaining 

 portion of the space having only the subperitoneal areolar tissue and the trans- 

 versalis fascia between the peritoneum and the aponeurosis of the External oblique 

 muscle. 



In some cases the hernial protrusion escapes from the abdomen on the outer 

 side of the conjoined tendon, pushing before it the peritoneum, the subserous 

 areolar tissue, and the transversalis fascia. It then enters the inguinal canal, 

 passing along nearly its whole length, and finally emerges from the external ring, 

 receiving an investment from the intercolunmar fascia. The coverings of this 

 form of hernia are precisely similar to those investing the oblique form, with the 

 insignificant difference that the infundibuliform fascia is replaced by a portion 

 derived from the general layer of the transversalis fascia. 



In other cases and this is the more frequent variety the hernia is either forced 

 through the fibres of the conjoined tendon or the tendon is gradually distended in 

 front of it so as to form a complete investment for it. The intestine then enters 

 the lower end of the inguinal canal, escapes at the external ring lying on the 

 inner side of the cord, and receives additional coverings from the superficial fascia 

 and the integument. This form of hernia has the same coverings as the oblique 

 variety, excepting that the conjoined tendon is substituted for the Cremaster, and 

 the infundibuliform fascia is replaced by a portion derived from the general layer 

 of the transversalis fascia. 



The difference between the position of the neck of the sac in these two forms 

 of direct inguinal hernia has been referred, with some probability, to a difference 

 in the relative positions of the obliterated hypogastric artery and the deep 

 epigastric artery. When the course of the obliterated hypogastric artery cor- 

 responds pretty nearly with that of the deep epigastric the projection of these 

 arteries toward the cavity of the abdomen produces two fossae in the peritoneum. 

 The bottom of the external fossa of the peritoneum corresponds to the position of 

 the internal abdominal ring, and a hernia which distends and pushes out the peri- 

 toneum lining this fossa is an oblique hernia. When, on the other hand, the 

 obliterated hypogastric artery lies considerably to the inner side of the deep epi- 

 gastric artery, corresponding to the outer margin of the conjoined tendon, it divides 

 the triangle of Hesselbach into two parts, so that three depressions will be seen on 

 the inner surface of the lower part of the abdominal wall, viz., an external one, on 

 the outer side of the deep epigastric artery ; a middle one, between the deep 

 epigastric and the obliterated hypogastric arteries ; and an internal one, on the 

 inner side of the obliterated hypogastric artery (see page 1051). In such a case 

 a hernia may distend and push out the peritoneum forming the bottom of either 

 fossa. When the hernia distends and pushes out the peritoneum forming the 

 bottom of the external fossa, it is an oblique or external inguinal hernia. These 

 fossae are the inguinal fossce. 



When the hernia distends and pushes out the peritoneum forming the bottom 

 of either the middle or the internal fossa, it is a direct or internal hernia. 



The anatomical difference between these two forms of direct or internal 

 inguinal hernia is that, when the hernia protrudes through the middle fossa that 

 is, the fossa between the deep epigastric and the obliterated hypogastric arteries 

 it will enter the upper part of the inguinal canal ; consequently its coverings will be 



