The fibers which form a sling for the rectum are named the Puborectalis. They arise from the lower part of the pubic symphysis, and from the superior fascia of the urogenital diaphragm.They meet with the corresponding fibers of the opposite side around the lower part of the rectum, and form for it a strong sling. Relaxation increases the angle between rectum and anus, allowing defecation in conjunction with relaxation of theinternal and external anal sphincters. The puborectalis is part of the levator ani muscle.
The levator ani is a broad, thin muscle, situated on either side of thepelvis. It is formed from three muscle components: the puborectalis, the pubococcygeus muscle (of which the puborectalis is part of) and the iliococcygeus muscle.
The pubococcygeus muscle or PC muscle is a hammock-like muscle, found in both sexes, that stretches from the pubic bone to the coccyx (tail bone) forming the floor of the pelvic cavity and supporting the pelvic organs. It is part of the levator ani muscle.
The iliococcygeus muscle refers to the lateral part of the levator ani which belongs to pelvic diaphragm.