366 THE MUSCLES AND FASCIA 



front of them, forming the anterior wall of the crural sheath. Beneath Poupart's 

 ligament it is strengthened by a band of fibrous tissue, which is only loosely con- 

 nected to P}upart's ligament, and is specialized as the deep crural arch. The 

 spermatic cord in the male and the round ligament in the female pass through this 

 fascia ; the point where they pass through is called the internal abdominal ring. 

 This opening is not visible externally, owing to a prolongation of the transversalis 

 fascia on these structures, forming the infundibuliform fascia. 



The internal or deep abdominal ring is situated in the transversalis fascia, 

 midway between the anterior superior spine of the ilium and the symphysis pubis, 

 and about half an inch above Poupart's ligament. It is of an oval form, the 

 extremities of the oval directed upward and downward, varies in size in different 

 subjects, and is much larger in the male than in the female. It is bounded, above 

 and externally, by the arched fibres of the Transversalis ; below and internally, by 

 the deep epigastric vessels. It transmits the spermatic cord in the male and the 

 round ligament in the female. From its circumference a thin funnel-shaped 

 membrane, the infundibuliform fascia, is continued round the cord and testis, 

 enclosing them in a distinct pouch. 



When the sac of an oblique inguinal hernia passes through the internal or deep abdominal 

 ring, the infundibuliform process of the transversalis fascia forms one of its coverings. 



The inguinal or spermatic canal contains the spermatic cord in the male and 

 the round ligament in the female. It is an oblique canal about an inch and a half 

 in length, directed downward and inward, and placed parallel to and a little above 

 Poupart's ligament. It commences above at the internal or deep abdominal ring, 

 which is the point where the cord enters the spermatic canal, and terminates below 

 at the external ring. It is bounded in front by the integument and superficial 

 fascia, by the aponeurosis of the External oblique throughout its whole length, and 

 by the Internal oblique for its outer third ; behind, by the triangular fascia, the 

 conjoined tendon of the Internal oblique and Transversalis, transversalis fascia, 

 and the subperitoneal fat and peritoneum ; above, by the arched fibres of the 

 Internal oblique and Transversalis ; below, by Gimbernat's ligament, and by the 

 union of the fascia transversalis with Poupart's ligament. The deep epigastric 

 artery passes upward and inward behind the canal lying close to the inner side of 

 the internal abdominal ring. The interval between this artery and the outer edge 

 of the Rectus is named Hesselbach's triangle, the base of which is formed by 

 Poupart's ligament. 



That form of protrusion in which the intestine follows the course of the spermatic cord 

 along the spermatic canal is called oblique inguinal hernia. 



The Deep Crural Arch. Curving over the vessels, just at the point where they 

 become femoral, on the abdominal side of Poupart's ligament and loosely connected 

 with it, is a thickened band of fibres called the deep crural arch. It is apparently 

 a thickening of the fascia transversalis, joining externally to the centre of 

 Poupart's ligament, and arching across the front of the crural sheath to be inserted 

 by a broad attachment into the spine of the os pubis and ilio-pectineal line, behind 

 the conjoined tendon. In some subjects this structure is not very prominently 

 marked, and not infrequently it is altogether wanting. 



Surface Form. The only two muscles of this group which have any considerable influ- 

 ence on surface form are the External oblique and Rectus muscles of the abdomen. With 

 regard to the External oblique, the upper digitations of its origin from the ribs are well marked, 

 intermingled with the serrations of the Serratus magnus ; the lower digitations are not visible, 

 being covered by the thick border of the Latissimus dorsi. Its attachment to the crest of the 

 ilium, in conjunction with the Internal oblique, forms a thick oblique roll, which determines the 

 iliac furrow. Sometimes on the front of the lateral region of the abdomen an undulating out- 

 line marks the spot where the muscular fibres terminate and the aponeurosis commences. The 

 outer border of the Rectus is defined by the linea semilunarig, which may be exactly defined by 

 putting the muscle into action. It corresponds with a curved line, with its convexity outward, 

 drawn from the end of the cartilage of the ninth rib to the spine of the os pubis, so that 

 the centre of the line, at or near the umbilicus, is three inches from the median line. The 



