Anatomy of the pelvic floor and anal sphincters

Abstract

The pelvic floor is a striated muscular structure providing enclosure to the bladder, uterus, and rectum. It plays significant role in storage and evacuation of urine and stool. This article reviews the anatomy of the anal sphincters and the pelvic Ûoor. The internal and external anal sphincters are responsible for maintaining faecal continence at rest and when continence is threatened, respectively. Defecation is a somatovisceral reÛex regulated by dual nerve supply (i.e. somatic and autonomic) to the anorectum. The net effects of sympathetic and cholinergic stimulation are to increase and reduce anal resting pressure, respectively. Faecal incontinence and functional defecatory disorders may result from structural changes and/or functional disturbances in the mechanisms of faecal continence and defecation.