450 THE MUSCLES AND FASCIA 



what triangular in form, and corresponds with the course of the fibres of the 

 aponeurosis. It usually measures from base to apex about an inch, and 

 transversely about half an inch. It is bounded below by the crest of the os 

 pubis ; above, by a series of curved fibres, the inter columnar, which pass across 

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

 the margins of the opening in the aponeurosis, which are called the columns or 

 pillars of the ring. 



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

 direction, is the stronger : it is formed by that portion of Poupart's ligament 

 which is inserted into the spine of the os pubis ; it is curved so as to form a kind 

 of groove, upon which the spermatic cord rests. The internal or superior pillar 

 is a broad, thin, flat band which is attached to the front of the symphysis pubis, 

 interlacing with its fellow of the opposite side, that of the right side being super- 

 ficial. 



The external abdominal ring gives passage to the spermatic cord in the male, 

 and round ligament in the female : it is much larger in men than in women, on 

 account of the large size of the spermatic cord, and hence the greater frequency 

 of inguinal hernia in men. 



The intercolumnar fibres are a series of curved tendinous fibres, which arch 

 across the lower part of the aponeurosis df the External oblique. They have 

 received their name from stretching across between the two pillars of the external 

 ring, describing a curve Avith the convexity downward. They are much thicker 

 and stronger at the outer margin of the external ring, where they are connected 

 to the outer third of Poupart's ligament, than internally, where they are inserted 

 into the linea alba. They are more strongly developed in the male than in the 

 female. The intercolumnar fibres increase the strength of the lower part of the 

 aponeurosis, and prevent the divergence of the pillars from one another. 



These intercolumnar fibres as they pass across the external abdominal ring are 

 themselves connected together by delicate fibrous tissue, thus forming a fascia, 

 which^as it is attached to the pillars of the ring Covers it in, and^is called the 

 intercolumnar fascia. This intercolumnar fascia is continued down as a tubular 

 prolongation around the outer surface of the cord and testis, and encloses them in 

 a distinct sheath ; hence it is also called the external spermatic fascia. 



The sac of an inguinal hernia, in passing through the external abdominal ring, receives an 

 investment from the intercolumnar fascia. 



If the finger is introduced a short distance into the external abdominal ring 

 and the limb is then extended and rotated outward, the aponeurosis of the 

 External oblique, together with the iliac portion of the fascia lata, will be felt to 

 become tense, and the external ring much contracted ; if the limb is on the con- 

 trary flexed upon the pelvis and rotated inward, this aponeurosis will become lax 

 and the external abdominal ring sufficiently enlarged to admit the finger with 

 comparative ease : hence the patient should always be put in the latter position 

 when the taxis is applied for the reduction of an inguinal hernia in order that the 

 abdominal walls may be relaxed as much as possible. 



Poupart's ligament, or the crural arch, is the lower border of the aponeurosis of 

 the External oblique muscle, and extends from the anterior superior spine of 

 the ilium to the pubic spine. From this latter point it is reflected outward to be 

 attached to the pectineal line for about half an inch, forming Gimbernat's liga- 

 ment. Its general direction is curved downward toward the thigh, where it is 

 continuous with the fascia lata. Its outer half is rounded and oblique in direction. 

 Its inner half gradually widens at its attachment to the os pubis, is more horizontal 

 in direction, and lies beneath the spermatic cord. 



Nearly the whole of the space included betAveen the crural arch and the 

 innominate bone is filled in by the parts which descend from the abdomen into the 

 thigh. These will be referred to again on a subsequent page. 



Gimbernat's ligament is that part of the aponeurosis of the External oblique 



