2. Diagram the boundaries of the perineum, and understand the location and function of the perineal body.
The perineum is the region of the pelvis superficial to the pelvic floor, and may be best conceptualized as a diamond-shaped structure consisting of two non-coplanar triangles: the urogenital triangle and the anal triangle.
The urogenital triangle of the perineum consist of the following layers (superficial-to-deep):
- Superficial fatty (Camper’s) fascia
- Deep membranous (Colles’) fascia
- This layer is continuous with the Scarpa’s fascia of the abdomen
- Superficial perineal space (pouch)
- Ischiocavernosus mm. & Crura of clitoris/penis
- Bulbospongiosus mm. & Vestibular bulbs/bulb of the penis
- Greater vestibular (Bartholin’s) glands
- Superficial transverse perineal mm.
- Perineal membrane
- Deep perineal space (pouch)
- Compressor urethrae (external urethral sphincter)
- Deep transverse perineal mm.
- Bulbo-urethral (Cowper’s) glands
- Levator ani m. & perineal body
The anal triangle contains the anal canal and anal sphincters, and the ischio-anal (ischiorectal) fossae with pudendal canals.
The perineal body, a fibromuscular mass, sits on the midline between the urogenital and anal triangles, at the level of the muscles within the superficial perineal space and external anal sphincter. It may be palpated through the skin, but it may only be seen upon dissection into the superficial space of the urogenital triangle and anal triangle.