Muscles of the pelvic outlet


Any division that is initiated by a sheet of tissue is considered a diaphragm. The muscular wall at the base of the pelvic cavity is known as the pelvic outlet. This area is also known to have two distinctive diaphragms known as the urogenital diaphragm and the pelvic diaphragm. Immediately deep to the external genitals the urogential diaphragm can be located. The pelvic diaphragm is rests near the internal organs of the pelvic region. Both of these muscular sheets work in unison to provide ample support for the internal pelvic viscera as well as play a vital role in the regulation of the excretion of the body’s waste products.


The pelvic diaphragm is created by both the levator ani muscle and the coccygeus muscle. The levator ani is a slight sheet of muscle tissue. Its main purpose is to provide structural support for the internal viscera while simultaneously assisting in the process of defecation. By constricting the lower section of the rectum, the levator ani pulls the rectum forward to help solid wastes exit the body. The levator ani muscle is assisted greatly by the coccygeus muscle. The coccygeus muscle rests deeper within the body than the levator ani and resembles the shape of a fan.

The deeper diaphragm, the urogenital diaphragm, is created mostly by the transversus perinea muscle with a little help from the associated external muscles and the sphincter muscle. These two muscle work together to create a funnel within the anal canal. As constrictor muscles, they may be relied upon for the prevention of premature release of fecal matter as well as assist in appropriate fecal matter release.

The perineal muscles are responsible for aiding the structural support needed by the genitals. These muscle rest inferiorly to the pelvic diaphragm and offer the appropriate skeletal muscle support. The perineal muscles are created by the individual muscles known as the bulbocavernosus muscles, the ischiocavernosus muscles, as well as the superficial transversus perinea muscles.


With the exception of the perineal muscles, the remainder of the muscles of the pelvic diaphragm and the urogenital diaphragm are nearly identical in both the male and female bodies. The male body has a unified bulbospongiosus which allows for the muscle constriction at the base of the penis. When the urethra requires draining, these muscles contract in order to help constrict the urethral canal and assist the process of urination.

In the female body, these muscles are interrupted by the vaginal opening which sets the stage for the constriction around the vaginal orifice. When the muscles contract, there is noticeable constriction, and again the process of urination is assisted.

In the female body, the ischiocavernosus muscle’s insertion point runs along the pubic arch into the crus of the clitoris. In the male body, the insertion point runs along the pubic arch into the crus of the penis. The main effect of this muscle is achieving erection in males and clitoral erections in females during sexual arousal.
  Member Comments