ABDOMINAL AND PERINEAL FASCIiE. 325 



vessels lie in front of this part of the iliac fascia. To the outer side 

 of those vessels, the fascia turns forwards to be connected with Poupart's 

 ligament and the fiiscia transversalis, as already described ; to the inner 

 side of the femoral vein it is attached to the ilio-pectineal line, alono- 

 with the fascia lata ; and between these two points, namely, behind the 

 femoral vessels, it continues downwards over the margin of the pelvis, 

 forming the back part of the sheath of those vessels. 



The psoas parvus is closely connected with the iliac fascia, by means 

 of an expansion of its tendon. 



At the back part of the abdomen there is also a thin but strong 

 fascia covering the quadratus lumborum muscle and forming the 

 anterior layer of the lumbar aponeurosis. It is attached at the 

 outer border of the quadratus to the middle layer of the aponeurosis, 

 and at its inner border to the roots of the transverse processes of the 

 lumbar vertebra. Superiorly it forms two strong bands, the ligamenta 

 arcuata of the diaphragm already described, and inferiorly it is attached 

 to the crest of the ilium. 



The middle layer of the lumbar aponeurosis consists of strong 

 fibrous bundles which are attached to the posterior layer at the outer 

 margin of the erector spinae. It intervenes between that muscle and 

 the quadratus, and is attached internally by three or four slips to the 

 tips of the lumbar transverse processes. It gives origin at its outer 

 part to the middle fibres of the transversalis abdominis muscle. 



MUSCLES AND FASCIiE OF THE PERINiEUM AND PELVIS. 



Fascia of the Perineum — Superficial Fascia. — In the posterior 

 half of the perimeum the subcutaneous fat is continued deeply into the 

 ischio-rectal fossa, the pyramidal space intervening between the obtu- 

 rator fascia and the levator ani muscle. In the anterior half of the 

 periuEeum, beneath the subcutaneous fat, is placed a special layer of 

 fascia, continuous with the dartos, the 'proper superficial perineal fascia, 

 sometimes called fascia of Colles. This fascia is bound down on each 

 side to the margin of the pubic arch as far back as the ischial tuber- 

 osity ; posteriorly, along a line from the ischial tuberosity to the central 

 point of the perinajum, it turns round the posterior margin of the 

 transversus perin^i muscle to join the subpubic fascia, to be presently 

 described. From its deep surface likewise, an incomplete septum in 

 the middle line dips down to the urethra and passes iorwards into the 

 scrotum. It thus happens that air blown in beneath the proper perineal 

 fascia on one side passes forwards and distends the scrotum to a certain 

 extent on that side ; it may then penetrate to the other also, and if 

 injected with sufficient force may reach the front of the abdomen, and 

 travel upwards beneath the superficial fascia ; but it neither passes 

 backwards to the posterior half of the perinacum nor down upon the 

 thighs. The same course is followed by urine or matter extravasated 

 beneath the proper perineal fascia. 



The deep perineal or subpubic fascia is stretched across the 

 pubic arch on the deep surface of the crura of the penis and the bulb 

 of the urethi-a. It consists of two distinct layers of strong fibrous 

 membrane, separated by intervening structures. The anterior layer, or 

 triangular ligament of the urethra, attached to the inferior margin of the 



