puborectalis muscle
The fibers which form a sling for the rectum are named the Puborectalis or Sphincter recti. They arise from the lower part of the symphysis pubis, 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 reduces the angle between rectum and anus, allowing defecation in conjunction with relaxation of the internal and external sphincters. Puborectalis is part of the levator ani group of muscles.