258 MUSCLES AND FASCIA OF THE ABDOMEN. 



The parts of the superficial fascia here described have received minute attention 

 from surgical anatomists, because of their close relation to the seat of hernial 

 tumours : the adhesion of the fascia to Poupart's ligament, and its disposition over 

 the inguinal aperture, spermatic cord, and scrotum, while they prevent the descent 

 upon the thigh of matter which has been effused beneath the fascia, cause it rather to 

 spread upwards upon the abdomen or to take its course downwards upon the scrotum. 



The deep layer of the abdominal fascia is also interesting, as corresponding with 

 the tunica abdominalis, a strong membrane consisting almost entirely of yellow 

 elastic tissue, which exists in animals, as may be well seen in the horse or ox, and 

 which contributes to the support of the viscera. 



Lining fascia of the abdomen. On the inner surface of the wall of 

 the abdomen is a membranous structure which lines the visceral aspect of 

 the deepest stratum of muscles ; it. is divisible into two principal parts, 

 the fascia transversalis and fascia iliaca. 



The fascia transversalis is named from its position on the deep surface of 

 the transversalis muscle. It is strongest and most clearly demonstrable in 

 the lower part, where the muscular and tendinous support is somewhat 

 weaker ; and here also it is of particular interest, on account of its forming 

 one of the coverings for inguinal hernia. Followed upwards from this 

 situation, the transversalis fascia becomes gradually less strong, and beyond the 

 margin of the ribs it degenerates into a thin covering for the under surface 

 of the diaphragm. Along the inner surface of the iliac crest, between the 

 iliacus and transversalis muscles, the fascia is attached to the periosteum. 

 For about two inches inwards from the anterior superior iliac spine, it is 

 closely connected with the posterior surface of Poupart's ligament, and is 

 there directly continuous with the fascia iliaca, a white line sometimes mark- 

 ing the place of continuity. At this place also, and to the same extent, the 

 fascia lata is closely united with both the fascia transversalis and Poupart's 

 ligament, which thuj serves as a line of union of several layers of fascia. 

 About midway between the iliac spine and the pubes, the external iliac 

 artery and vein, as they pass out into the thigh, intervene between the fascia 

 transversalis and the fascia iliaca, and from this point to the edge of Giin- 

 bernat's ligament the fascia transversalis is prolonged downwards under the 

 crural arch, and over the artery and vein, forming the anterior portion of 

 the funnel-shaped femoral sheath. This prolongation of the fascia trans- 

 versalis passes under Poupart's ligament, and is not very closely united 

 with it : it is strengthened by a dense band of fibres which arches over 

 the vessels, and is inserted into the pubic crest and pectineal line behind 

 the conjoined tendon of the transversalis and internal oblique. This 

 band is sometimes called the deep crural arch. It includes beneath it, 

 internal to the vessels, a space between Gimbernat's ligament and the 

 vein, sufficiently large to admit the point of the little finger ; this is 

 called the crural ring, and is the space through which femoral hernia 

 descends. About half way between the anterior superior iliac spine and 

 the symphysis pubis, and about half an inch above Poupart's liga- 

 ment, the spermatic cord in the male, or the round ligament in the female, 

 pierces the fascia transversalis. The opening thus made is called the internal 

 or deep abdominal ring, to distinguish it from the external or superficial 

 ring in the aponeurosis of the external oblique muscle ; the fascia above and 

 internal to it is thin, but below and external to it is firm and thick, and 

 forms a distinct crescentic margin, over which the cord or round ligament 

 passes ; from the borders of the opening a delicate funnel-shaped covering, 

 the infundibuliform fascia, is prolonged downwards on the emerging struc- 



