OF THE ABDOMEN. 457 



midway between the anterior superior spine of the ilium and the spine of the os 

 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 Trans versalis ; 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 ligament, 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 the union of the fascia transversalis 

 with 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. Passing across the front of the crural arch, on the 

 abdominal side of Poupart's ligament and closely 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 pectineal line, behind the conjoined tendons. In some subjects this 

 structure is not very prominently marked, and not unfrequently 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 Hnea semilunaris, which may be exactly defined by 

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

 drawn from the lowest part of the cartilage of the seventh 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 

 inner border of the Rectus corresponds to the linea alba, marked on the surface of the body by 

 a groove, the abdominal furrow, which extends from the infrasternal fossa to, or to a little below, 

 the umbilicus, where it gradually becomes lost. The surface of the Rectus presents three trans- 

 verse furrows, the linece transversce. The upper two of these, one opposite or a little below the 

 tip of the ensiform cartilage, and another, midway between this point and the umbilicus, are 

 usually well marked ; the third, opposite the umbilicus, is not so distinct. The umbilicus, situ- 

 ated in the linea alba, varies very much in position as regards its height. It is always situated 

 above a zone drawn round the body opposite the highest point of the crest of the ilium, gene- 

 rally being about three-quarters of an inch to an inch above this line. It generally corresponds, 

 therefore, to the fibro-cartilage between the third and fourth lumbar vertebra?. 



Deep Muscles of the Abdomen. 



Psoas parvus. Iliacus.r 



Psoas magnus. Quadratus lumborum. 



