Neuronal innervation of urethral and anal sphincters: surgical anatomy andclinical implications

The present review describes the neuronal innervation of the external ureth ral and anal sphincters, A knowledge of this innervation helps in understan ding the clinical symptoms of urinary and anorectal pathology, and in choos ing the appropriate technique of nerve localization or block. An ability to locate the pudendal nerve, on the basis of surgically documented anatomy, has important diagnostic and therapeutic advantages. It can be used to stud y the integrity of pelvic floor muscles, in biofeedback training, nerve blo cks, pudendal canal decompression, chronic stimulation trials to treat urin ary or faecal incontinence, and in nerve conduction studies or evoked poten tial recordings. Furthermore, the superficial location of the sphincteric i nnervation in the perineum and ischiorectal fossa renders the nerve branche s susceptible to injury during operative correction of urinary or faecal in continence. Supported by a knowledge of anatomy, we can make firm recommend ations on which to base safe surgical techniques that avoid damage to ureth ral and anal sphincteric innervation. (C) 2000 Lippincott Williams & Wilkin s.