Dr. Sherine Aubert describes the bulbocavernosus muscle, part of the superficial (or outermost) layer of the pelvic floor.
Bulbocavernosus is primarily a sphincteric (constricts and relaxes to allow passage in or out) and sexual muscle. It is located under the pubic bones, attaching the erectile (meaning filling with blood) tissues, circling around the vaginal opening, and attaching to the perineal body. Its purpose is to help create clitoral erections and close the vaginal opening.