56 ANATOMY OF THE GROIN : HERNIA, 



(3 - 5 cm.) transversely at its base. In this area the abdominal wall consists of, 

 besides the integuments, 1, the aponeurosis of the external oblique muscle, which 

 is perforated towards the lower and inner corner of the space by the external 

 abdominal ring ; 2, the inner portion of the cremaster muscle covering the sper- 

 matic cord at the lower and outer part of the space, and above this the lower 

 fibres of the internal oblique and transversalis muscles passing to their insertion by 

 the conjoined tendon, which, as a rule, extends over the inner two-thirds of the 

 lower part of the triangle ; 3, transversalis fascia ; 4, subperitoneal tissue ; and 5, 

 peritoneum. 



The conjoined tendon varies greatly in its development. In many cases it is very slight, 

 and scarcely to be distinguished, while in others its deeper portion, derived from the trans- 

 versalis muscle, covers the whole breadth of the triangle, reaching outwards along the deep 

 femoral arch as far as the internal abdominal ring (fig. 23, left side). Sometimes the outer 

 part is detached from the rest, and forms a band which has been designated lig amentum 

 interfoveolare or ligament of Hesselbacft, while to the remaining inner portion the name of / fa; 

 inguinalis or ligament of Henle has been given. (See W. His, in die anatomiselie Nomenclatur, 

 1895, p. 121 ; and K. M. Douglas, The Anatomy of the Transversalis Muscle 'and its Relation 

 to Inguinal Hernia, Journ. Anat., xxiv, 1890.) 



The distance of the obliterated hypogastric artery from the middle line, and with it the 

 breadth of the fovea supravesicalis, is also subject to variation. In most cases, however, the 

 hypogastric cord ascends altogether behind the rectus muscle, and therefore an internal hernia 

 will project in the mesial inguinal fossa. Only in rare cases does a hernia protrude in the 

 supravesical hollow, between the obliterated hypogastric artery and the edge of the rectus. 



A hernia emerging to the inner side of the epigastric vessels in the majority of 

 cases protrudes in the inner part of the triangle of Hesselbach, and is forced onwards 

 directly into the external abdominal ring. The coverings of such a hernia, taking 

 them in the order in which they are successively applied to the protruded viscus, are 

 the following : The peritoneal sac and the subperitoneal tissue which adheres to it, 

 the transversalis fascia, the conjoined tendon of the internal oblique and transversalis 

 muscles, and the spermatic fascia derived from the margin of the external abdominal 

 ring, together with the superficial fascia and skin. With regard to the conjoined 

 tendon, this hernia may be covered by it, or may pass through an opening in its 

 fibres. 



The spermatic cord is commonly placed behind the outer part of the hernia. The 

 hernial sac is not, however, in contact with the vessels of the cord, the investments, 

 given from the transversalis fascia to those vessels and to the hernia respectively, as 

 well as the cremasteric fascia, being interposed. 



But the spot at which an internal inguinal hernia passes through the triangle of 

 Hesselbach is subject to some variation, and there is a second form of internal 

 hernia which differs somewhat in its course and relations from the foregoing. In 

 this variety the hernia protrudes to the outer side of the conjoined tendon, between 

 that and the epigastric vessels. Such a protrusion passes through a considerable 

 portion of the inguinal canal to reach the external ring, and has therefore a certain 

 degree of obliquity, whence this variety is frequently termed internal oblique, inguinal 

 hernia. It is also known as superior internal hernia, the direct form being called 

 inferior internal. As an internal oblique hernia passes outside the conjoined tendon, 

 it has no covering derived from that structure, but it receives one from the cremaster 

 in the same way as an external hernia. 



Direct inguinal hernia is very rarely met with in the female. In the single case 

 observed by Richard Quain, as well as in the few cases found recorded in books, the 

 hernia though not inconsiderable in size was still covered by the tendon of the 

 external oblique muscle. 



