These muscles can develop TrPs. The bulbospongiosus essentially wraps around the corpus spongiosum of the penis, which is the central erectile structure through which the urethra passes. The anterior and middle fibers of the bulbospongiosus and ischiocavernosus muscles contribute to erection by reflex and voluntary contraction that compresses the erectile tissue of the bulb of the penis and also its dorsal vein. Contraction of the ischiocavernosus muscle maintains and enhances penile erection by retarding the return of blood through the penis. The piriformis is a major intrapelvic muscle which is a frequent site of TrPs.
Entrapments are numerous.
Exiting the pelvis along the lower border of the piriformis are the pudendal nerve and blood vessels. The pudendal nerve innervates the bulbocavernosus, ischiocavernosus, and sphincter urethrae membranacea muscles and the skin and corpus cavernosus of the penis. Patients may complain of . . . sexual dysfunction . . . This is a complex area with multiple layered muscles and opportunities for entrapment. After a surgical procedure, such as a hernia repair, a regimen of stretches can often help prevent adhesions and TrPs.