Muscles of the female perineum. (Bulbocavernosus visible at upper right.)
Muscles of male perineum. (Bulbocavernosus visible at upper left.)
|Actions||in males, empties the urethra; in females, clenches the vagina|
|Anatomical terms of muscle|
Bulbospongiosus (bulbocavernosus in older texts) is one of the superficial muscles of the perineum. It has a slightly different origin, insertion and function in males and females. In males, it covers the bulb of the penis. In females, it covers the vestibular bulb.
Its fibers diverge like the barbs of a quill-pen; the most posterior form a thin layer, which is lost on the inferior fascia of the urogenital diaphragm; the middle fibers encircle the bulb and adjacent parts, of the corpus cavernosum urethræ, and join with the fibers of the opposite side, on the upper part of the corpus cavernosum urethræ, in a strong aponeurosis; the anterior fibers, spread out over the side of the corpus cavernosum penis, to be inserted partly into that body, anterior to the Ischiocavernosus, occasionally extending to the pubis, and partly ending in a tendinous expansion which covers the dorsal vessels of the penis.
The latter fibers are best seen by dividing the muscle longitudinally, and reflecting it from the surface of the corpus cavernosum urethræ.
This muscle serves to empty the canal of the urethra, after the bladder has expelled its contents; during the greater part of the act of micturition its fibers are relaxed, and it only comes into action at the end of the process.
The middle fibers are supposed by Krause to assist in the erection of the corpus cavernosum urethræ, by compressing the erectile tissue of the bulb.
The anterior fibers also contribute to the erection of the penis by compressing the deep dorsal vein of the penis as they are inserted into, and continuous with, the fascia of the penis.
|Wikimedia Commons has media related to Bulbospongiosus muscle.|
- Origin, insertion and nerve supply of the muscle at Loyola University Chicago Stritch School of Medicine
- -838467507 at GPnotebook
- Anatomy photo:41:11-0102 at the SUNY Downstate Medical Center—"The Female Perineum: Muscles of the Superficial Perineal Pouch"
- Anatomy figure: 42:04-02 at Human Anatomy Online, SUNY Downstate Medical Center—"Muscles of the male superficial perineal pouch."
- Anatomy figure: 43:04-11 at Human Anatomy Online, SUNY Downstate Medical Center—"The urinary bladder and the urethra as seen in a frontal section of the female pelvis."
- SUNY Anatomy Image 9162
- SUNY Anatomy Image 9197