THE ABDOMEN 679 



stricture in an internal direct inguinal hernia may be (i) at the external 

 abdominal ring, (2) at the fissure in the conjoined tendon, if that structure 

 should be ruptured, or (3) at the neck of the sac. The latter situation is 

 the most common, and it is to be noted that the deep epigastric vessels lie 

 on the cuter side of the neck of the sac. 



Internal Oblique Inguinal Hernia. — This variety is called internal because 

 the hernia, as it leaves the abdominal cavity, is internal to the deep epigastric- 

 artery, and oblique, because it has to descend through the lower two-thirds 

 of the inguinal canal. The course of this variety is as follows : the hernia 

 enters the middle inguinal fossa, elongating before it the peritoneum forming 

 that fossa. It then passes through the outer third of Hesselbach's triangle 

 and descends through the lower two-thirds of the inguinal canal, from which 

 it emerges through the external abdominal ring into the scrotum, thus forming 

 a complete internal oblique inguinal hernia. Practically the only difference 

 between the course of an internal oblique and an external oblique inguinal 

 hernia is that the external oblique variety enters the inguinal canal by its 

 natural inlet, namely, the internal abdominal ring, whereas the internal oblique 

 variety obtrudes itself into the upper part of the inguinal canal through its 

 posterior wall. It is to be noted (i) that there is no natural opening in the 

 fascia transversalis over the outer third of Hesselbach's triangle, as there is 

 external to the deep epigastric artery, and (2) that there is no conjoined 

 tendon over the outer third of Hesselbach's triangle. The coverings of tliis 

 variety, enumerated in order from within outwards, are as follows : 



1. Parietal peritoneum. 



2. Subperitoneal fat or areolar tissue. 



3. Fascia transversalis. 



4. Cremasteric or middle spermatic fascia. 



5. Intercolumnar or external spermatic fascia. 



6. Tunica dartos. 



7. Skin. 



If the coverings of an external oblique, and an internal oblique, inguinal 

 hernia are compared with each other, it will be seen that the former has a 

 tube of fascia transversahs already prepared for it. namely, the infundibuliform 

 fascia, whereas the latter has to elongate before it a fresh portion of fascia 

 transversalis. In some cases the fascia transversahs over the outer third of 

 Hesselbach's triangle is covered by an expansion from the conjoined tendon, 

 which is known as the reflected tendon of Cooper. In such cases that reflected 

 tendon must be added as a covering of internal obUque inguinal hernia, its 

 position being immediately superficial to the covering formed by the fascia 

 transversalis. The relation of an internal oblique inguinal hernia to the 

 spermatic cord is similar to that of an external obUque, and the possible seats 

 of stricture are also similar. The neck of the sac is the most common situa- 

 tion, and the deep epigastric vessels he immediately on its outer side. The 

 extreme difficulty which must be experienced in diagnosing between an 

 external obhque and an internal obUque hernia is explained by the fact that 

 the former leaves the abdominal cavity immediately external to the deep 

 epigastric vessels, and the latter immediately internal to them. Hence, the 

 practical rule followed in operating is to cut upwards and not transversely. 

 The propriety of this rule is further enhanced if it be remembered that an 

 external oblique inguinal hernia of old standing may so drag upon the internal 

 abdominal ring as to displace it do\\Tiwards and inwards to a point behind 

 the external ring, and thus a hernia which is really external oblique may 

 simulate one of the internal direct variety. 



Varieties of External ObUque Inguinal Hernia. — There are two varieties 

 of this form of hernia, the special features of which depend upon abnormal 

 conditions of the processus vaginalis (see p. 673). These varieties are named 

 congenital and infantile.' 



Congenital Hernia.^There are two forms of congenital hernia, (i) The 

 processus vaginalis may remain permanently open throughout, in which 

 case the bowel descends within that process into the ca\aty of the tunica 

 vaginaUs at its lower extremit\\ The tunica vaginalis thus represents the 



