THE ABDOMINAL WALLS 263 



avoided. In all cases where the canal is artificially narrowed, 

 the surgeon must guard against closing it too tightly lest undue 

 pressure be exerted on the spermatic cord. 



Oblique inguinal hernia of long duration and great size tends 

 to take a more and more direct course through the abdominal 

 wall. The neck of the hernia gradually enlarges the abdominal 

 inguinal ring downwards and medially, until it comes to lie 

 directly behind the subcutaneous inguinal ring. In these cases, 

 after the hernia has been reduced, the examining ringer can be 

 passed directly backwards through the abdominal wall into the 

 abdomen. This alteration in the direction of the inguinal canal 

 is necessarily accompanied by an alteration in the direction 

 taken by the inferior epigastric artery. It now passes medially 

 to the pubic tubercle (spine) and then ascends behind the lateral 

 border of the rectus abdominis. 



Direct Inguinal Hernia. In the lower part of the anterior 

 abdominal wall the Triangle of Hesselbach can be identified. 

 Its base is formed by the medial end of the inguinal ligament, 

 its medial side by the lateral border of the rectus abdominis, 

 and its lateral side by the inferior epigastric artery, which 

 separates the triangle from the abdominal inguinal ring. 

 Occasionally, hernia occurs through the fascia transversalis in 

 the floor of Hesselbach's triangle. This variety, known as 

 a Direct (or Internal} Hernia, enters the inguinal canal at its 

 medial end arid immediately opposite the subcutaneous inguinal 

 (ext. abd.) ring. In doing so, it usually passes directly through 

 the falx inguinalis (conjoined tendon), though it may appear at 

 its lateral margin. Its subsequent course is the same as that of 

 an oblique hernia. The most important difference between 

 these two varieties (the direct and the oblique) lies in their 

 relationship to the inferior epigastric artery. The neck of the 

 sac of an oblique hernia is placed lateral to the artery, while 

 the neck of the sac of a direct hernia is medial to the vessel 



(Fig. 77)- 



In a case of old-standing inguinal hernia some difficulty 

 may be experienced in deciding which of the two varieties is 

 present, as in both cases the hernial opening is large and the 

 exploring ringer will pass directly through the abdominal wall. 

 Should such a hernia become strangulated, the surgeon will be 

 well advised to incise the constricting neck of the sac in an 

 upward and medial direction, in order to avoid the inferior 

 epigastric vessels. For if he mistakes a direct for an oblique 



