84 TOPOGRAPHICAL ANATOMY OF THE 



greater part of the tendon is aponeurotic, and blends with the corre- 

 sponding tendinous aponeurosis of the internal oblique muscle, thus 

 gaining the linea alba. The fused aponeuroses form the ventral part 

 of the sheath of the straight abdominal muscle. 



A considerable band of tendinous fibres stretches from the tuber 

 coxae to the pecten of the pubis lateral to the symphysis. This band is 

 generally designated the inguinal ligament of Poupart, ^ or the lateral 

 crus of the aponeurosis — that part connected with the linea alba being 

 the medial crus. The ligament curves in a dorsal and cranial direction, 

 gradually becoming thinner antl finally blending with the iliac fascia. 

 It will also be observed that fibres from the ligament are continued into 

 the fascia on the medial as|)ect of the thigh. 



Laterally the medial and lateral crura of the aponeurosis become 

 indistinguishably blended ; but in the vicinity of the pubis they are 

 separated by a slit-like opening, the subcutaneous inguinal ring 

 (annulus inguinalis subcutaueus), which is the ventral or outer end of 

 the inguinal canal. 



Dissection. — Until such time as it is possil)le to make a complete 

 examination of the inguinal canal, the dissection of the abdominal tvall 

 should he limited to one side of the body. 



Make an incision through the fleshy part of the external oblique 

 muscle close to the line along which it joins the aponeurosis. A trans- 

 verse incision about midway between the tuber coxae and the last rib 

 will permit the turning aside of the fleshy part of the muscle, so that 

 the examination of the internal oblique muscle may be proceeded with. 



M. OBLIQUUS INTERNUS ABDOMINIS. — The internal oblique abdom- 

 inal muscle is entirely covered by the preceding, and consists of fleshy 

 fibres arranged in a fan-like manner radiating from the region of the 

 tuber coxse. Its origin is fleshy, and form the coxal tuber and the 

 adjacent part of the inguinal ligament of Poupart. The most dorsal 

 fibres pursue a slightly oblique course to end, by flattened tendons, on 

 the inner surface of the cartilages of the last four or five ribs. The 

 fibres of the rest of the muscle follow a course of varying obliquity and> 

 about the lateral margin of the straight abdominal muscle, become 

 continuous with a broad aponeurotic tendon by which insertion to the 

 linea alba is gained. 



The aponeuroses of the two oblique muscles are blended to form the 

 ventral part of the sheath of the straight muscle ; but, it will be noticed, 

 the blending is least extensive near the pubis and gradually increases 

 as the xiphoid region is approached. 



What doubtless ought to be regarded as a partially or completely 

 isolated part of the internal oblique is frequently described as an 



1 Francois Poupart, a French anatomist, 1661-1709. 



