The pelvic floor is made up of three main muscles - the levator ani, puborectalis, and coccygeus. The levator ani forms the main part of the pelvic diaphragm and separates the pelvis from the perineum below. It has three parts - puborectalis, pubococcygeus, and iliococcygeus. The coccygeus is located posterior to the levator ani. These muscles work to support the pelvic viscera, maintain continence, and allow functions like voiding, defecation, and childbirth. Injury to the pelvic floor muscles during childbirth can cause prolapse of the uterus.