ABSTRACT
Gross continence depends almost entirely on the action of the anal sphincter muscles. The anal sampling reflex described in laboratory studies has been confirmed as a common anorectal event using ambulatory studies. The sensory supply to the mucosal lining of the anal canal is complex. Sensory fibers in the pudendal nerve almost certainly supply the lower anal canal and the perianal skin and the direct branches entering superiorly into the levators and puborectalis from the sacral plexus also carry sensory fibers from the posterior urethra and upper anal canal. Normal subjects successfully discriminate between flatus and solid. Consequently a method of assessing temperature awareness in the anal canal might prove useful for research purposes. The measurements were made in the upper, middle, and lower thirds of the anal canal as previously defined using manometry. Routine anorectal sensory assessment therefore involves evaluation of anal canal sensation, along with measurement of rectal perception.
