Muscle of Perineum

Muscle: Bulbospongiosus

Origin:

Male - Median raphe on ventral surface of bulb of penis; perineal body

Female - Perineal body

Course and Distribution:

Male - Surrounds lateral aspects of bulb of penis and most proximal part of body of penis, inserting into perineal membrane, dorsal aspect of corpus spongiosum and corpora cavernosa, and fascia of bulb of penis

Female - Passes on each side of lower vagina, enclosing bulb and greater vestibular gland; inserts into pubic arch and fascia of corpora cavernosa of clitoris

Innervation: Muscular (deep) branch of perineal nerve, a branch of pudendal nerve (S₂-S₄)

Main Action(s):

Male - Supports and fixes perineal body/pelvic floor; compresses bulb of penis to expel last drops of urine/semen; assists erection by compressing outflow via deep perineal vein and by pushing blood from bulb into body of penis

Female - Supports and fixes perineal body/pelvic floor; "sphincter" of vagina; assists in erection of clitoris (and perhaps bulb of vestibule); compresses greater vestibular gland