Bulbospongiosus muscle

Bulbospongiosus muscle
File:Bulbospongiosus-Female.png Muscles of the female perineum. (Bulbocavernosus visible at upper right.)
File:Bulbospongiosus-Male.png Muscles of male perineum. (Bulbocavernosus visible at upper left.)
Details
Latin	musculus bulbospongiosus
Origin	Median raphé
Artery	Perineal artery
Nerve	pudendal nerve
Actions	in males, empties the urethra; in females, clenches the vagina
Identifiers
Dorlands /Elsevier	m_22/12548543
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terms of muscle [[[d:|edit on Wikidata]]]

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.

In both sexes, it is innervated by the deep/muscular branch of the perineal nerve, which is a branch of the pudendal nerve.

Structure

The bulbospongiosus is located in the middle line of the perineum, in front of the anus. It consists of two symmetrical parts, united along the median line by a tendinous raphé.

It arises from the central tendinous point of the perineum and from the median raphé in front.

Fibers

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.

Function

In males it contributes to erection, the contractions of orgasm and ejaculation. In females it contributes to clitoral erection and the contractions of orgasm, and closes the vagina.

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 spongiosum, 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.

Gallery

• 

  Coronal section of anterior part of the male pelvis, through the pubic arch. Seen from in front.

• 

  The superficial branches of the internal pudendal artery in the male.

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

External links

• -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."
• Anatomy image:9162 at the SUNY Downstate Medical Center
• Anatomy image:9197 at the SUNY Downstate Medical Center