1408 



SUKFACE AND SUKGICAL ANATOMY. 



muscular fibres of the external oblique, is another slight triangular depression, 

 which corresponds to the inferior and narrow part of the aponeurosis of the external 

 oblique muscle. 



Close above, and almost parallel to, the medial half of the inguinal ligament 

 is the inguinal canal, traversed by the spermatic funiculus (Fig. 1101); the latter 

 can be felt to emerge at the subcutaneous inguinal ring immediately above the 

 pubic tubercle. The abdominal and subcutaneous inguinal rings have been fully 

 described elsewhere; the former is triangular in shape, with its apex directed 

 superiorly and laterally, and its base immediately above the pubic crest. By 

 invaginating the skin of the scrotum the little finger may be passed through the 

 ring into the canal. It is to be noted that the neck of an inguinal hernia lies 

 above the pubic tubercle, whereas the neck of a femoral hernia emerges below the 

 medial end of the inguinal ligament, lateral to the pubic tubercle. The abdominal 

 inguinal ring, an opening in the fascia transversalis, lies half an inch above a 



Obliquus externus abdominis 



Obliquus interims abdominis 



Obliquus interims 



abdominis (cut) 



Deep circumflex iliac artery 



Abdominal inguinal ring and 

 internal spermatic fascia 



Cremaster muscle 

 Obliquus externus abdominis 



Spermatic funiculus passing 

 through cremaster muscle 



)bliquus externus abdominis 

 bliquus internus abdominis (cut) 



Transversus abdominis 



Over inferior epigastric artery 



Fascia transversalis 



Inferior epigastric artery 



Falx aponeurotica inguinal is 



Over lateral border of rectus abdominis 



Spermatic funiculus 



Lig. retiexum inguinale 



FIG. 1101. THE GROIN. The structures seen on reflection of part of the obliquus internus abdominis 



(A. M. Paterson). 



point a little medial to the middle of the inguinal ligament. The inferior epi- 

 gastric artery may be mapped out by drawing a line from a point midway between 

 the superior anterior iliac spine and the symphysis pubis towards the umbilicus. 

 The vessel, together with the medial third of the inguinal ligament and the 

 inferior part . of the lateral border of the rectus, bounds a triangle known as 

 Hesselbach's triangle. As the inferior epigastric artery passes superiorly and 

 medially to disappear behind the falx aponeurotica inguinalis and the lateral 

 border of the rectus, it lies behind the spermatic funiculus immediately medial 

 to, and below, the abdominal inguinal ring. The floor of Hesselbach's triangle 

 is formed throughout by the fascia transversalis, superficial to which, over the 

 medial half or so of the triangle, is the falx aponeurotica inguinalis. An oblique 

 inguinal hernia leaves the abdomen at the abdominal inguinal ring and traverses 

 the whole length of the inguinal canal ; its coverings are therefore the same as 

 those of the spermatic funiculus, and the neck of the sac lies lateral to the 

 inferior epigastric artery, hence this variety of hernia is also termed lateral inguinal 

 hernia. A direct inguinal hernia, on the other hand, instead of traversing the 

 whole length of the inguinal canal, pushes before it that part of its posterior 

 wall which is formed by the floor of Hesselbach's triangle. The neck of the sac, 

 therefore, lies medial to the inferior epigastric artery, and this variety of hernia 

 may be termed a medial inguinal hernia. If a direct hernia makes its way 

 through the medial part of Hesselbach's triangle, it derives a covering from the 



