The internal and external anal sphincters along with the puborectalis muscle allow the feces to be passed by pulling the anus up over the exiting feces in shortening and contracting actions.
22.
A weakened puborectalis leads to widening of the anorectal angle, and impaired barrier to stool in the rectum entering the anal canal, and this is associated with incontinence to solids.
23.
This arrangement means that when puborectalis is contracted, it pulls the junction of the rectum and the anal canal forwards, creating an angle in the bowel called the anorectal angle.
24.
The point at which the rectum joins the anal canal is known as the anorectal ring, which is at the level that the puborectalis muscle loops around the bowel from in front.
25.
In patients with anismus, the puborectalis and the external anal sphincter muscles fail to relax, with resultant failure of the anorectal angle to straighten out and facilitate evacuation of feces from the rectum.
