PRACTICAL CONSIDERATIONS : ABDOMINAL HERNIA. 1765 



peritoneal pouch which extends into the scrotum. For a time free communication 

 with the abdominal cavity is maintained by the now tubular processus vaginalis ; 

 usually, however, by the time of birth, or shortly after, this canal is obliterated, the 

 isolated lower end of the peritoneal pouch persisting as the sac of the tunica vaginalis 

 which almost surrounds the testicle. The peritoneal evagination occurs in both 

 sexes, in the female extending into the labium majus as the diverticulum of Nuck ; 

 this usually early disappears, but, as a great rarity, may remain as an open peritoneal 

 process at the time of puberty (Merkel). 



If obliteration of the processus vaginalis does not occur, a congenital hernial sac 

 results (Fig. 1488 ), and this may become a hernia, either at birth or in later life, by 

 the descent of some of the abdominal viscera. During their descent the testicle and 

 spermatic cord obtain more or less extensive investments of such parts of the abdomi- 

 nal walls as have taken part in the formation of the original bursa ingualis. From 

 within outward these would be, therefore, ( i ) peritoneiim, after obliteration of the 

 stalk of the peritoneal pouch, however, coextensive with only the tunica vaginalis ; 

 (2) infundibiili/orm fascia (tunica vaginalis communis), continued from the trans- 



FlG. i486. 



Internal oblique, cut and 

 turned outward 



Transversalis muscle 



Aponeurosis of external — ^ 

 oblique I 



External abdominal ring 



Saphenous openin: 



Aponeurosis of external oblique, 

 cut edge 



Aponeurosis of internal 

 oblique, cut edge 



Internal abdominal ring; 

 cord covered by infundib- 

 uliform fascia 



Transversalis fascia (weak spot) 



Conjoined tendon 



Triangular fascia 



Dissection of right inguinal canal ; external and internal oblique cut and reflected, exposing transversalis muscle. 



versalis fascia ; (3) cremaster fibres, from the transversalis and internal oblique mus- 

 cles, blended by areolar tissue into the cremasteric fascia ; (4) intercolumnar fascia, 

 from the aponeurosis of the external oblique. In addition to these coverings from 

 the abdominal wall, the envelopes forming the scrotum proper contribute (5) the 

 modified superficial fascia or tunica dartos and (6) the skin. LTnusual attachments 

 of the gubernaculum below to the tuber ischii and sphincter ani account for some of 

 the forms of testicular ectopia (q.v.). Attachments above to the peritoneum of the 

 caecum or ileum, or of the sigmoid, or to the loosely attached peritoneum lining the 

 iliac fossa, account in part for the formation of the sac in infantile hernia {vide infra). 



The strength of the attachments of the gubernacula to the testes and to the dartos 

 is shown by the fact that in cases of elephantiasis scroti, although the enormously 

 thickened skin and dartos may form a tumor reaching to the knee, the testicles will 

 usually be found near its lower extremity. 



The next step in the anatomical study of inguinal hernia should consist in a 

 survey of the inner surface of the abdominal cavity in the inguinal, iliac, and hypo- 

 gastric regions (Fig. 14S7 ). This will show that the space between the lateral wall 

 of the abdomen and the mid-line — marked by the peritoneal fold over the urachus 



