282 



MUSCLES AND FASCIA. 



the latter to the pectineal line, a few fibres pass upwards and inwards beneath the 

 inner pillar of the ring, to the linea alba. They diverge as they ascend, and form 

 a thin, triangular, fibrous band, which is called the triangular ligament. 



In the aponeurosis of the External oblique, immediately above the crest of the 

 os pubis, is a triangular opening, the external abdominal ring, formed by a sepa- 

 ration of the fibres of the apoueurosis in this situation ; it serves for the trans- 

 mission of the spermatic cord in the male, and the round ligament in the female. 



Fig. 163. The External Oblique Muscle. 



This opening is directed obliquely upwards and outwards, and 'corresponds with 

 the course of the fibres of the aponeurosis. It is bounded, below, by the crest of 

 the os pubis ; above, by some curved fibres, which pass across the aponeurosis at 

 the upper angle of the ring, so as to increase its strength ; and, on either side, by 

 the margins of the aponeurosis, which are called the pillars of the ring. Of 

 these, the external, which is, at the same time, inferior, from the obliquity of its 

 direction, is inserted into the spine of the os pubis. The internal or superior 



