Bulbospongiosus muscle
Bulbospongiosus compresses the bulb of the penis or vaginal orifice, supporting erection.
The bulbospongiosus is a paired superficial perineal muscle located in the urogenital triangle. It differs anatomically between males and females but serves related functions involving urethral compression, ejaculation, clitoral erection, and stabilization of pelvic structures. It overlies erectile tissues—specifically, the bulb of the penis in males and the bulb of the vestibule in females. It is innervated by the deep branch of the perineal nerve (from the pudendal nerve, S2–S4).
Structure
The bulbospongiosus is a striated muscle made of skeletal fibers. It varies slightly in morphology between sexes but maintains a similar pattern of origin, insertion, and layered organization within the superficial perineal pouch.
Origin and Insertion
- Origin: Perineal body (central tendon of perineum)
- Insertion (male): Perineal membrane and corpus spongiosum of penis
- Insertion (female): Pubic arch, fascia of corpora cavernosa, and bulb of vestibule
Differences by Sex
- Male: Single midline muscle wrapping around the bulb of the penis and proximal corpus spongiosum
- Female: Bilateral muscles flanking the vestibule of the vagina, surrounding the bulb of the vestibule and greater vestibular glands
Location
The bulbospongiosus muscle is situated within the superficial perineal pouch of the urogenital triangle, superficial to the perineal membrane.
Direction | Related Structures (Male) | Related Structures (Female) |
---|---|---|
Deep | Bulb of penis, corpus spongiosum | Bulb of vestibule, greater vestibular gland |
Superficial | Perineal fascia and skin of scrotum | Perineal fascia and labia |
Medial | Midline fusion over bulb of penis | Vestibule of vagina |
Function
- Male:
- Compresses bulb of penis during ejaculation and urination
- Aids in emptying urethra of residual urine or semen
- Contributes to erection by compressing deep dorsal vein of penis
- Female:
- Compresses greater vestibular glands during sexual arousal
- Tenses vagina and contributes to clitoral erection
Innervation
- Deep branch of perineal nerve (branch of pudendal nerve, S2–S4)
Blood Supply
- Perineal branches of the internal pudendal artery
Clinical Significance
- Perineal trauma: Can be involved in obstetric tears (females)
- Dysfunction: Weakness or hypertonicity may contribute to sexual dysfunction or pelvic floor disorders
- Surgical landmark: Important during repair of perineal tears and urogenital surgeries
Last updated on May 11, 2025