The deep layer of superficial fascia (Colles' Fascia) is thin, aponeurotic in structure, and of considerable strength, serving to bind down the muscles of the root of the penis. Colles fascia, also known as perineal fascia, emerges from the perineal membrane, which divides the base of the penis from the prostate. Colles fascia emerges from the inferior side of the perineal membrane and continues along the ventral (inferior) penis without covering the scrotum. It separates the skin and subcutaneous fat from the superficial perineal pouch.
This fascia not only covers the muscles in this region, but at its back part sends upward a vertical septum from its deep surface, which separates the posterior portion of the subjacent space into two.