[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Pelvis](https://durgical.com/en/anatomy/region/pelvis/) › Bulbospongiosus [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Pelvis](https://durgical.com/en/anatomy/region/pelvis/) # Bulbospongiosus The bulbospongiosus is a thin muscle on each side of the vaginal opening; it narrows the opening and helps the clitoris become erect. Official name: Bulbospongiosus muscle [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=pelvis&variant=male&select=bulbospongiosus&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A muscle that wraps the bulb of the penis; its two halves join in the midline. ## What it does Empties the last drops of urine from the urethra, helps with erection and pushes semen out at ejaculation. ## Key points - Female: its two halves are separated by the vaginal orifice. Male: they join in a midline raphe over the bulb of the penis - Male: it empties the last urine from the [spongy urethra](https://durgical.com/en/anatomy/spongy-urethra/) and contracts rhythmically to expel semen - With the ischiocavernosus and the [superficial transverse perineal muscle](https://durgical.com/en/anatomy/superficial-transverse-perineal-muscle/) it outlines a small triangle on each side, floored by the [perineal membrane](https://durgical.com/en/anatomy/perineal-membrane/) ## Key facts **Origin** Perineal body **Insertion** Around the vaginal orifice over the vestibular bulbs to the perineal membrane and the body of the clitoris **Action** Constricts the vaginal orifice; compresses the vestibular bulbs and the [greater vestibular gland](https://durgical.com/en/anatomy/greater-vestibular-gland/); aids clitoral erection **Nerve** Perineal branch of [pudendal nerve](https://durgical.com/en/anatomy/pudendal-nerve/) (S2–S4) **Blood supply** Perineal branch of [internal pudendal artery](https://durgical.com/en/anatomy/internal-pudendal-artery/) ## Relations **Deep** The vestibular bulb, with the Bartholin gland at its posterior end (male: the bulb of the penis) **Medial** The vaginal orifice and the vestibule **Lateral** The [ischiocavernosus](https://durgical.com/en/anatomy/ischiocavernosus-muscle/) over the crus of the [clitoris](https://durgical.com/en/anatomy/clitoris/) **Behind** The [perineal body](https://durgical.com/en/anatomy/perineal-body/), where it blends with the [external anal sphincter](https://durgical.com/en/anatomy/external-anal-sphincter/) and the transverse perineal muscles **Superficial** Colles fascia and the fat of the labium majus ## How to find it Not seen as a separate muscle on examination; in dissection, after Colles fascia is removed, it is the thin sheet curving around the vaginal orifice over the vestibular bulb. ## Examination - Bulbocavernosus reflex: squeezing the glans of the clitoris or penis (or tugging a urinary catheter) makes the anal sphincter contract; it tests S2–S4, and its return marks the end of spinal shock ## On imaging Not assessed on radiographs. On axial and coronal MRI of the perineum it is a thin muscle curving over the vestibular bulb on each side of the vaginal opening. It is seldom reported on its own: MRI and transperineal ultrasound are used to study the perineum after birth injury, a Bartholin cyst at its back end, and masses or congenital anomalies of the vulva. ## Common problems - Straddle injuries (falling astride a bar or a beam) can bruise the perineum and tear the urethra. - Perineal pain or numbness, for example from long cycling. ## How it is diagnosed Examination; ultrasound or MRI when needed. ## Treatment - Depends on the cause: rest, a better bicycle seat, or treatment of a urethral injury by a urologist. ## Clinical notes - Torn in second-degree tears and cut in an episiotomy; its ends are brought together to rebuild the perineal body - Involuntary tightening of the muscles around the vaginal opening, this one included, is part of genito-pelvic pain disorders (formerly vaginismus) - Male: a straddle fall crushes the bulbar urethra against the pubis beneath this muscle ## Development Its shape follows the external genitalia: in the male the urethral folds fuse in the midline, leaving the raphe, and the two halves of the muscle meet over the bulb; in the female the folds stay apart as the [labia minora](https://durgical.com/en/anatomy/labium-minus-of-vulva/) and the muscle stays split around the vestibule. ## Related conditions - [Obstetric perineal tears and anal sphincter injury](https://durgical.com/en/conditions/obstetric-perineal-tears-and-anal-sphincter-injury/) - [Erectile dysfunction](https://durgical.com/en/conditions/erectile-dysfunction/) ## Test yourself Think of the answer, then tap the question to see it. ## How is the bulbospongiosus arranged in the female compared with the male? Female: two halves separated by the vaginal orifice, over the vestibular bulbs. Male: halves joined in a midline raphe over the bulb of the penis. ## What does the bulbocavernosus reflex test, and how is it elicited? S2–S4: squeezing the glans of the clitoris or penis (or tugging a catheter) makes the anal sphincter contract; its return marks the end of spinal shock. ## In which perineal injuries is the bulbospongiosus torn or cut? Second-degree tears and episiotomy; its ends are brought together to rebuild the perineal body. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/bulbospongiosus-muscle/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus bulbospongiosus TA2 2418 **Official Spanish (DeCS)** Músculo bulboesponjoso **English (TA2)** Bulbospongiosus muscle **Also called** musculus bulbocavernosus ## Related - [Corpus spongiosum](https://durgical.com/en/anatomy/corpus-spongiosum-of-penis/) - [Perineal body](https://durgical.com/en/anatomy/perineal-body/) - [Perineal membrane](https://durgical.com/en/anatomy/perineal-membrane/) - [Pudendal nerve](https://durgical.com/en/anatomy/pudendal-nerve/) - [Internal pudendal artery](https://durgical.com/en/anatomy/internal-pudendal-artery/) Sources: Terminologia Anatomica (TA2); [Anatomy, Abdomen and Pelvis: Superficial Perineal Space](https://www.ncbi.nlm.nih.gov/books/NBK542289/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/bulbospongiosus-muscle/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/bulbospongiosus-muscle/