THE ILIAC AND LUMBAR FASCIA. 337 



the infundibuliform fascia, is prolonged downwards on the emerging structures, and 

 this forms in cases of oblique hernia one of the coverings of the tumour. 



The iliac fascia, stronger than the transversalis fascia, lines the back part of 

 the abdominal cavity, and covers the ilio-psoas muscle. The densest portion is 

 stretched transversely from the iliac crest, over the iliacus and psoas, to the brim of 

 the pelvis, where it is attached to the iliac portion of the ilio-pectineal line. A 

 thinner part is continued upwards on the surface of the psoas, along the inner 

 border of which it is attached to the sacrum, to the inter vertebral discs and the 

 neighbouring margins of the lumbar vertebrae, as well as to the tendinous arches 

 over the lumbar vessels (p. 243). Externally, it joins the anterior layer of the 

 lumbar fascia ; and above, it becomes blended with the internal arched ligament of 

 the diaphragm. Inferiorly the iliac fascia is prolonged downwards, covering the 

 conjoined muscle, a short distance into the thigh, being placed behind the femoral 

 artery and vein, and forming the hinder portion of the femoral sheath. On the 

 outer side of the vessels, the fascia as it descends is closely united with the lower 

 border of the transversalis fascia and Poupart's ligament, and it ends by blending 

 with the fascia lata forming the upper part of the sheath of the sartorius. Internally 

 this part of the fascia becomes directly continuous with the pubic portion of the 

 fascia lata (see p. 242), while from the junction of the two a short but strong inter- 

 muscular septum is sent backwards between the psoas and pectineus muscles to be 

 attached to the ilio-pectineal eminence and the capsule of the hip-joint. 



In cases where the psoas parvus is present the iliac fascia is thickened above the 

 ilio-pectineal eminence by the incorporation of the tendon of this muscle as it 

 expands to its insertion. 



At the back part of the abdomen there is also a thin membrane covering the 

 quadratus lumborum muscle and forming the anterior layer of the lumbar 

 fascia. It is attached at the inner border of the quadratus to the front of the 

 transverse processes of the lumbar vertebrae, while along the outer border of that 

 muscle it becomes united with the middle layer of the fascia. Superiorly it forms 

 the external arched ligament of the diaphragm already described, and inferiorly it is 

 attached to the ilio-lumbar ligament and the crest of the ilium. 



The middle layer of the lumbar fascia, much stronger than the anterior, 

 and placed between the erector spinse and quadratus lumborum, is formed by the 

 posterior aponeurosis of the transversalis muscle, in connection with which it has 

 already been described (p. 



MUSCLES AND FASCLffil OF THE PEBINEUM AND PELVIS. 



FASCIAE OF THE PERINEUM Superficial fascia. In the posterior half of 

 the perineum the subcutaneous fat is continued deeply into the ischio-rectal fossa, 

 the pyramidal space intervening between the obturator fascia and the levator ani 

 muscle. In the anterior half of the perineum, beneath the subcutaneous fat, is 

 placed a special layer of fascia, continuous with the dartos, the proper superficial 

 perineal fascia, sometimes called fascia of Colks. This fascia is bound down on 

 each side to the margin of the rami of the pubis and ischium as far back as the 

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

 point of the perineum, it turns round the hinder margin of the transversus 

 perinei muscle to join the deep perineal fascia, to be presently described. From 

 its deep surface, likewise, an incomplete median septum passes upwards towards 

 the urethra and is continued forwards 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 



