Perineal membrane

The perineal membrane is an anatomical term for a fibrous membrane in the perineum attached on each side to the inferior ramus fo the pubis and the ramus of the ischium that covers the inferior surface of the perineal muscles.

The perineal membrane is the superior border of the superficial perineal space (superficial perineal pouch), and the inferior border of the deep perineal space (deep perineal pouch).

The perineal membrane is triangular in shape. It attaches to both ischiopubic rami of the pelvis. It also attaches to the perineal body. Its base is directed toward the rectum, and connected to the central tendinous point of the perineum. The base is fused with both the with the inferior layer of the inferior fascia of pelvic diaphragm and membranous layer of perineal subcutaneous tissue (Colle's fascia)..

Its anterior margin is separated from the inferior aspect of the pubic symphysis by a small gap, through which passes the vena dorsalis penis profunda in male and the vena dorsalis profunda clitoris in female.

If the inferior fascia of the urogenital diaphragm is detached on either side, the following structures will be seen between it and the superior fascia:

• the deep dorsal vein of the penis

• the membranous portion of the urethra

• the deep transverse perineal muscle and the urethral sphincter muscles

• the bulbourethral glands and their ducts

• the pudendal arteries and dorsal nerves of the penis

• the arteries and nerves of the urethral bulb

• a plexus of veins