Bulbospongiosus (bulbocavernosus) surrounds the penile bulb and corpus spongiosum in males, and the vaginal orifice and vestibular bulbs in females. It is a key muscle of the perineal body and superficial perineal pouch. Its rhythmic contraction during orgasm contributes to the contractile phase of orgasm in both sexes.
| Origin | In males: central perineal body and median raphe over the bulb of the penis; In females: central perineal body |
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| Insertion | In males: dorsal surface of the corpus spongiosum and the corpus cavernosum; In females: clitoral body and perineal membrane |
| Nerve Supply | Deep perineal nerve (branch of pudendal nerve, S2-S4) |
| Blood Supply | Perineal artery branches |
| Actions | In males: empties the bulbar urethra of residual urine and semen; assists erection by compressing the deep dorsal vein of the penis; In females: compresses the vestibular glands and contributes to clitoral erection; both sexes: compresses the perineal body |
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Bulbospongiosus injury in perineal trauma, obstetric lacerations, and pelvic fracture contributes to urinary incontinence and sexual dysfunction. The bulbocavernosus reflex (BCR) tests S3-S4 reflex arc integrity: squeezing the glans penis or clitoris produces reflex anal sphincter contraction. An intact BCR in the context of flaccid paralysis after spinal cord injury confirms upper motor neuron injury above the sacral cord. Perineal reconstruction after trauma or radical prostatectomy may require bulbospongiosus transposition to cover the urethral anastomosis.
Pelvic fracture with perineal disruption tears the bulbospongiosus muscle at the perineal body, contributing to urethral disruption, sexual dysfunction, and stress incontinence; repair of the perineal body with restoration of bulbospongiosus midline union is part of urethral reconstruction and restores both continence and erectile function.
