MUSCLES OF THE ABDOMEN. 543 



incision along the ribs, just below its origin; a second incis- 

 ion is to be made from the anterior superior spinous pro- 

 cess transversely through the aponeurotic tendon of the 

 external oblique, to the linea alba, extending the incision 

 along the crest of the ilium. The external ring and pillars 

 will thus be left entire for subsequent examination. Dis- 

 sect from behind forward and in the course of the fibres of 

 the muscle. 



This muscle takes one of its names from the most of its 

 muscular fibres pursuing an upward direction. It arises 

 tendinous from the fascia lumborum, tendinous and fleshy 

 from the whole of the crest of the ilium, and fleshy from the 

 upper half of Poupart's ligament. The fibres of this muscle 

 do not all ascend, those at the lower part pursue rather a 

 transverse and downward direction. The fleshy portion is 

 continued farther forward than the external oblique, and 

 ends in a flat tendon, which at the outer edge of the rectus 

 divides into two layers, one of which unites with the tendon 

 of the external oblique to go in front of the rectus, the other 

 joins the tendon of the transversalis and passes behind the 

 rectus, thus forming a complete sheath for this muscle. 

 About half way between the umbilicus and pubis, the 

 whole of these tendons pass in front of the rectus, leaving 

 this muscle to rest upon the peritoneum. The internal 

 oblique is inserted tendinous into the ensiform cartilage, 

 and the whole length of the linea alba, tendinous into the 

 cartilages of the seventh and eighth ribs, and fleshy into 

 the cartilages of the four inferior ribs, function. The 

 same as external oblique. 



Transversalis abdominis. Dissection. Remove the inter- 

 nal oblique by incisions from the ribs above, and crest of 

 the ilium and Poupart's ligament below. The dissection 

 should begin near the crest of the ilium, as here will be 

 seen an artery, the circumflexa ilii, and some cellular tissue, 

 showing distinctly the line of separation between the two 

 muscles. The fibres of this muscle run transversely. It 

 arises tendinous from the fascia lumborum, from the inner 

 margin of the whole crest of the ilium, fleshy anteriorly 



