[TA] compound muscle of pelvis; formed by pubococcygeus and iliococcygeus muscles; origin, posterior body of pubis, tendinous arch of the levator ani (obturator fascia), and spine of ischium; insertion, anococcygeal ligament, sides of the lower part of the sacrum and of coccyx; action, resists prolapsing forces and draws the anus upward following defecation; supports the pelvic viscera; nerve supply, nerve to levator ani (fourth sacral spinal nerve). SYN: musculus levator ani [TA], elevator muscle of anus.