The levator ani is a group of striated muscles with a very important role in pelvic organ support (Fig. 1.2). It is practically the most important supportive structure of the pelvis and forms together with its fascial structures the pelvic diaphragm. It is funnel-shaped and is covered superiorly and inferiorly by connective tissue forming the superior and inferior fasciae of the levator; it is perforated by the urethra, vagina and anal canal as they exteriorize on the perineum. The levator ani is formed by three muscles: pubococcygeus, iliococcygeus and puborectalis muscles. It is frequently damaged during childbirth, mainly with instrumental deliveries [1]. The pubococcygeus is made of puboperinealis, puboanalis and pubovaginalis muscles, according to muscle fibers’ insertion. It is named sometimes also pubovisceral muscle because of its insertion on pelvic viscera. The boundaries between levator muscle components are vague and difficult to identify anatomically. The complexity of the levator structure and function is the cause of the confusion in its description and terminology in the literature. Kearney et al. reviewed the literature regarding the origin and insertion points as well as the terminology used to describe the levator and its components (Table 1.1) [2].

The pubococcygeus muscle originates from the inner surface of the pubic bone; its course runs inferiorly and medially to insert into the lateral vaginal walls (pubovaginalis), perineal body (puboperinealis) and anal wall, at the line corresponding to the intersphincteric groove between the two components of anal sphincter (internal and external). The puborectalis muscle is U-shaped, surrounding the anorectal junction.

The iliococcygeus muscle originates laterally from the arcus tendineus levator ani and inner surface of the ischial spines; it forms most of the levator plate. A few fibers attach the inferior sacrum and coccyx, but most of them join the opposite fibers to form the anococcygeal raphe; the raphe continues with the anococcygeal ligament.

The role of levator ani is mainly supportive. The pubovaginalis supports the lateral vaginal walls and indirectly the urethra, participating in the continence mechanism. The puboperinealis narrows the genital hiatus drawing the perineal body towards the symphysis pubis during contraction. The puboanalis contributes to the narrowing of genital hiatus and elevates the anus. The puborectalis muscle elevates the anorectal junction and is considered part of the anal sphincteric mechanism. The iliococcygeus muscle has an important role in pelvic support, as already mentioned. The levator ani muscle has some particularities that make it different from other muscles: (1) the permanent muscle tone contributes to the normal pelvic support, except during voiding or defecation; (2) it contracts rapidly with coughing or sneezing, maintaining continence; (3) it is distended during labour and delivery, maintaining integrity in the majority of cases, and then contracts and regains normal function [3].