As with the superficial fascia of the abdominal wall, the perineal fascia has a membranous layer on its deep surface. This membranous layer (Colles’ fascia), is attached: posteriorly to the perineal membrane and therefore does not extend into the anal triangle (Fig. 5.75), and to the ischiopubic rami that form the lateral borders of the urogenital triangle and therefore does not extend into the thigh (Fig. 5.75).