ii 



: 



PARIETES OP THE ABDOMEN. 165 



The OBLIQUUS INTERNUS MUSCLE arises from the outer 

 half of Ponpart's ligament, from the anterior two-thirds of 

 the crest of the iliuin, and from that portion of the lumbar 

 fascia which is attached to the spinous processes of the 

 lumbar vertebrae. The fibres of the lower part of this mus- 

 cle are thin, and separated from each other ; they curve 

 over the spermatic cord, or round ligament, and uniting 

 with the tendon of the muscle beneath, under the name of 

 the conjoined tendon of the internal oblique and trans- 

 versalis muscles, are inserted into the crest of the pubes 

 and the pectineal line behind the tendon of the external 

 oblique. The remainder of the fibres pass upward and 

 inward, and terminate in an aponeurosis at the outer 

 order of the rectus muscle. The upper half of this 

 poneurosis splits into two laminae, which encase the 

 pper half of that muscle, and meet on the median line ; 

 the whole of the aponeurosis passes in front of the lower 

 half of the muscle, blending with the tendon of the ex- 

 ternal oblique. Along the linea alba, the tendons of the 

 two sides unite inseparably. Superiorly the muscle is in- 

 serted into the lower border of the cartilages of the last 

 four ribs. 



In arching over the spermatic cord, certain of the muscu- 

 lar fibres are prolonged, and carried downward, in long 

 loops, by the testicles at the period of their descent ; these 

 fibres may be seen as a muscular layer upon the cord, and 

 are called the cremaster muscle ; they vary very much in 

 distinctness, and do not exist in the female subject. They 

 are sometimes described as coming from the transversalis 

 muscle, as well as the internal oblique, the two muscles 

 being intimately blended at this point. 



The separation of this muscle from the next is with difficulty 

 accomplished in a manner which leaves the transversalis neatly and 

 fairly exposed. The fibres of the internal oblique should be divided 

 transversely to their direction ; the different direction of its fibres and 

 the ramifications of vessels in the space between the muscles, will tell 

 when the transversalis is reached ; the internal oblique is to be dis- 

 sected away from it, and divided from its own tendon along the outer 

 edge of the rectus muscle. The lower fibres, which assume a similar 

 direction to those of the transversalis, and to a certain extent become 

 confounded with them, may be left behind, with reference to a more 

 special examination of the inguinal region in relation to hernia. 



The TRANSVERSALIS MUSCLE arises from the outer half 

 of Poupart's ligament, from the anterior three-fourths of 



