The bulbospongiosus is the thick extrapelvic continuation of the urethralis. It originates from the perineal body (and midline raphe over corpus spongiosum in male) and inserts at the superficial perineal membrane and dorsal penile or clitoral aponeurosis. In males, the bulbospongiosus muscles are united and surround the base of the penis. They aid in emptying of urine and ejaculate from urethra. In females, these muscles are separated in the middle by the vagina and act to constrict the vaginal introitus. They can also stop the flow of blood into veins, which maintains an erection in the penis of the male and the clitoris of the female. Its nerve connection is the perineal branch of the pudendal nerve (S2, 3, 4). [ http://en.wikipedia.org/wiki/Bulbospongiosus_muscle ]