levator ani, one of a pair of muscles of the pelvic diaphragm that stretches across the bottom of the pelvic cavity like a hammock, supporting the pelvic organs. It is a broad, thin muscle that separates into the pubococcygeus and the iliococcygeus. It originates from the ramus of the pubic bone, the spine of the ischium, and a band of fascia between the pubis and the ischium; it inserts into the last two segments of the coccyx, the anococcygeal raphe, the sphincter ani externus, and the central tendinous point of the perineum. The left and right levator ani muscles are divided ventrally but converge as a single sheet across the midline dorsally, forming most of the pelvic diaphragm. The levator ani is innervated by branches of the pudendal plexus, which contains fibers from the fourth sacral nerve. It functions to support and slightly raise the pelvic floor. The pubococcygeus draws the anus toward the pubis and constricts it. Compare coccygeus.
