1190 *T THE SURGICAL ANATOMY OF HERNIA. 



At the lower part of the abdominal Avail is a triangular space (Ifesselbaeh's 

 triangle], bounded externally by the deep epigastric artery covered by peritoneum 

 (plica epigastriea), internally by the margin of the Rectus muscle, below by Pou- 

 part's ligament. The conjoined tendon is stretched across the inner two-thirds of 

 this space, the remaining portion of the space having only the subperitoneal areo- 

 lar tissue and the transversalis 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 intercolumnar 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 fascia transversalis. 



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 fascia transversalis. N 



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

 of direct inguinal hernia has been referred, Avith 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 Avith that of the deep epigastric which is regarded as the 

 normal arrangement the projection of these arteries toAvard 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 peritoneum 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 epigastric artery, corresponding to the 

 outer margin of the conjoined tendon, the projection of the peritoneum over it 

 (plica hypogastricd) divides the triangle of Hesselbach into tAA'o parts, so that 

 three depressions will be seen on the inner surface of the lower part of the abdom- 

 inal 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. In 

 such a case a hernia may distend and push 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 betAveen 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 wUl be 

 the same as those of an oblique hernia, with the insignificant difference that the 

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

 the fascia transversalis, whereas Avhen the hernia protrudes through the internal 

 fossa it 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 part of the inguinal canal, and escapes from the 

 external abdominal ring lying on the inner side of the cord. 



