Neural control of the sexual response

The PFM are actively involved in the sexual response. Their activation has been mostly explored in males during ejaculation, where their repetitive activation during a several seconds interval is responsible for the expulsion of semen from the urethra, particularly by the bulbocavernosus muscles.

Little is known on PFM activity patterns during other parts of the human sexual response cycle. It is assumed that apart from general changes in muscle tone set by the emotional motor system, the sacral reflex circuitry governs much of the PFM activity during the sexual response cycle. The bulbocavernosus reflex behaviour, as known from studies would allow for reflex activation of the PFM during genital stimulation. Tonic stimulation of the reflex is postulated to hinder venous outflow from penis/clitoris, thus helping erection.

Reflex contraction of the PFM should conceivably contribute to the achievement of the ‘orgasmic platform’ (contraction of the levator ani and – in the female – the circumvaginal muscles). Climax in humans (in both sexes, and in experimental animals) elicits rhythmic contractions of the PFM/perineal muscles, which in the male drives the ejaculate from the urethra (assisted by a coordinated bladder neck closure).