<prompt> Which of the following is the largest and most impoant muscle in the pelvic floor?CoccygeusExternal anal sphincterLevator aniObturator internus  <response>: The pelvic floor is formed by the large levator ani with pas including the pubococcygeus, puborectalis, and iliococcygeus and the much smaller coccygeus. The small external anal sphincter lies below the levator ani and is not technically pa of the pelvic floor. The obturator internus is in the lateral wall of the pelvis. Ref: Hoffman B.L., Schorge J.O., Schaffer J.I., Halvorson L.M., Bradshaw K.D., Cunningham F.G., Calver L.E. 2012. Chapter 38. Anatomy. In B.L. Hoffman, J.O. Schorge, J.I. Schaffer, L.M. Halvorson, K.D. Bradshaw, F.G. Cunningham, L.E. Calver Eds, Williams Gynecology, 2e. 