288 



DISSECTION OF THE ABDOMEN. 



floor, 

 and roof. 



Canal in the 

 female. 



Internal 



abdominal 



ring: 



situation, 



form and 

 margin ; 



relations/, 



parts trans- 

 mitted 

 through it. 



External 



abdominal 



ring: 



situation. 



The intes- 

 tine, follow- 

 ing the 

 course of 

 the cord, 



has cover- 

 ings of the 

 peritoneum 

 and fat, 

 transver- 

 salis fascia, 



cremaster, 



spermatic 

 fascia, 

 superficial 

 fascia and 

 skin; 



fascia derived from the external oblique behind the external 

 abdominal ring (fig. 97, p. 263). 



Its floor is formed (1) by the meeting of the transversalis fascia 

 with Poupart's ligament, and (2) by the fibres of Poupart's ligament 

 inserted into the pectineal line (Gimbernat's ligament). Its roof is 

 formed (1) by the meeting of its anterior and posterior walls, arid (2) 

 by the lower arched borders of the internal oblique and transversalis. 



In the female, the canal has the same boundaries, but is usually 

 somewhat longer and narrower. In that sex it lodges the round 

 ligament. 



The internal abdominal ring (tig. 106) is an aperture in the 

 transversalis fascia, which is situate midway between the symphysis 

 pubis and the anterior superior iliac spine, and half an inch above 

 Poupart's ligament. It is oval in form ; and its longest diameter, 

 which is directed vertically, measures about half an inch ; the 

 fascia at its outer and lower parts is stronger than at the opposite 

 sides. 



Arching above and on the inner side of the aperture is the lower 

 border of the transversalis muscle (D), which is fleshy in the outer 

 but tendinous in the inner half. Beloiv is Poupart's ligament, 

 which separates the aperture from the external iliac artery. On the 

 inner side its limit is best marked, being formed by the deep 

 epigastric vessels. 



This opening in the transversalis fascia is the inlet to the inguinal 

 canal, and through it the cord, or the round ligament, passes into 

 the wall of the abdomen. An external hernia enters the canal at 

 the same spot, and all the protruding parts receive as a covering 

 the prolongation (infundibuliform fascia) from the fascial margin 

 of the opening. 



The external abdominal ring (fig. 97) is the outlet of the inguinal 

 canal, and through it the spermatic cord reaches the surface 

 of the body. This aperture is placed in the aponeurosis of the 

 external oblique muscle, near the crest of the pubis ; and from the 

 margin a prolongation (spermatic fascia) is sent on the parts passing 

 through it (p. 267). 



COURSE AND COVERINGS OF AN EXTERNAL, OR OBLIQUE HERNIA. 



A piece of intestine leaving the abdomen with the cord, and passing 

 through the inguinal canal to the surface of the body, will obtain a 

 covering from every stratum of the wall of the abdomen in the groin, 

 except from the transversalis muscle. 



It therefore receives its investments in this order : As the intestine 

 is thrust forwards, it carries before it first the peritoneum and the 

 subperitoneal fat, and enters the tube of the infundibuliform fascia 

 around the cord. Still increasing in size, it is forced downwards to 

 the lower border of the internal oblique muscle, where it has 

 the cremasteric fascia applied to it. The intestine is next directed 

 along the front of the cord to the external abdominal ring, and in 

 passing through that opening receives the investment of the inter- 

 columnar or spermatic fascia. Lastly, as the hernia descends towards 



