It consists of two symmetrical parts, united along the median line by a tendinous perineal raphe.

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

[2] Its fibers diverge; 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 urethrae, and join with the fibers of the opposite side, on the upper part of the corpus cavernosum urethrae, 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.

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 urination 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.