Anorectal anatomy and physiology.

Knowledge of anorectal anatomy is essential for understanding the normal function of the anorectum. Its physiology is more complex, however. The maintenance of continence depends on several factors, and today clinicians have a better understanding of the usual sequence of events that leads to defecation. The extensive number of investigative techniques that have evolved have permitted better understanding of the disorders of the anal sphincters, rectum, and pelvic floor.