The role of the levator ani muscle in evacuation, sexual performance and pelvic floor disorders.

This paper reviews the role of the levator ani muscle (LAM) in evacuation, sexual performance and pelvic floor disorders. The LAM fixes the vesical neck, anorectal junction and vaginal fornices to the side wall of the pelvis by means of the suspensory sling and hiatal ligament. On contraction it shares in the mechanism of evacuation (urination, defecation). During the sexual act vaginal distension by the erect penis evokes the vaginolevator and vaginopuborectalis reflexes, with a resulting LAM contraction. The LAM also contracts upon stimulation of the clitoris or cervix uteri, an action mediated through clitoromotor and cervicomotor reflexes. LAM contraction leads to upper vagina ballooning, which acts as receptacle for semen collection, to uterine elevation and straightening and to elongation and narrowing of the vagina. These actions enhance the sexual response and prepare the uterus and vagina for the reproductive process. During ejaculation LAM contraction facilitates semen ejection. Levator subluxation and sagging leads to levator dysfunction syndrome, which may present as pudendal canal syndrome.