Perineum: Functional anatomy

Abstract

The perineum is the complex of tissues between the peritoneum and the skin that closes the pelvis inferiorly. The surface projection of the perineum and the form of the skin covering vary considerably depending on the position of the thighs: they are reduced when the tighs are adducted, whereas they widen when the tighs are flexed and abducted. The perineum is diamond-shaped, bounded by four lines: two from the pubic symphysis to the ischial tuberosities, and two from the ischial tuberosities to the coccyx. In the female, it is crossed anteriorly by the urethra and the vagina and posteriorly by the rectum; in the male, it is crossed anteriorly by the urethra and posteriorly by the rectum. Thus, in the female, the skin of the perineum is reduced compared with that in the male. Anatomical structures between the perineum and skin are constituted by muscles and fasciae, which are located in three planes: (1) the pelvic diaphragm, (2) the urogenital diaphragm, and (3) the superficial plane of the perineum. © 2008 Springer-Verlag Italia.