A 58-year-old mother of 10 suffers from fecal incontinence. Usually, defecation occurs by increased intraabdominal pressure via the Valsalva maneuver, increased rectal contraction, and relaxation of the puborectalis muscle, which forms a "sling" around the distal rectum, forming a relatively acute angle that distributes intra -abdominal forces onto the pelvic floor. With defecation, this angle straightens, allowing downward force to be applied along the axis of the rectum and anal, and opening of the anal canal. A dysfunction at which point of this pathway can lead to fecal incontinence?
A. Injury to the puborectalisDefecation proceeds by coordination of increasing intraabdominal pressure via the Valsalva maneuver, increased rectal contraction, relaxation of the puborectalis muscle, and opening of the anal canal. Impaired continence may result from poor rectal compliance, injury to the internal and/or external sphincter or puborectalis, or nerve damage or neuropathy.