Constipation symptoms can arise for a variety of different reasons. One of the most common causes of constipation is when the muscles of the rectum and/or pelvic floor are not working properly when attempting to pass stool during a bowel movement. This condition is referred to as dyssynergic defecation. Other names for this condition include anismus, pelvic floor dysfunction, paradoxical puborectalis dysfunction, anorectal muscle dysfunction, and outlet obstruction. The specific muscles that may be working improperly with dyssynergic defecation include the anal sphincter muscle and the puborectalis muscle. The anal sphincter is a circular muscle that helps keep the opening of the anus closed. Normally this muscle should relax when having a bowel movement. This allows the opening of the anus to become wider so that the stool can pass easily out of the rectum. The other muscle involved in defecation is the puborectalis muscle. This is a sling muscle that wraps around the rectum pinching it closed. This muscle should also normally relax when having a bowel movement. This allows the rectum to straighten providing easy movement of the stool through and out of the rectum. When either one or both of these muscles fails to properly relax during a bowel movement, this results in dyssynergic defecation.