The Role of the Voluntary Anal Sphincter in the Maintenance of Fæcal Continence in Normal and Abnormal States

Abstract

acetylcholine from fine nerve endings (Wright and Shepherd, 1965), but nicotine does not produce contraction of normal human sphincter muscle at any concentration.I t is possible that the nerve supply at this level is predominantly inhibitory, with relatively few motor fibres. An alternative would be that the motor fibres are not cholinergic.In summary it is apparent that the autonomic nerve supply of the gut is more complex than was previously thought. Studies in vivo and in vitro indicate that there are inhibitory nerves to the internal anal sphincter, and that relaxation occurs on stimulation of the thoracolumbar outflow. Whether these nerves are adrenergic and what neurohumoral agents are involved in relaxation either of the sphincter or of the rest of the hindgut are matters open to tlou1,t. REFERENCESManometric studies oit normal and abnormal chaldren showed that the voluntarv cphiizctcr complex of the anal c a w 1 siibserzvd the most important role in the maintriaaitrr nf roiitiiiriir(' by three incrlznwsiii r--lzaincly, b y provadtiig a resting prrsrztrr t i t the sphinrtrr m i c higlacr than that in the rectzim, by reflex contractions in response to rectal dirtcnsioiz, with coiarequriit unconrciozts adjustment of thr anal presrure to preserve continonce, a i d bv t t c actioiz ac (2 ronscious reJponre to reinforce the anal canal and control defacattoit Fitrthermorc, rtrrtrlz receptors in the voluntary sphincter complex of the anal canal gave a wartizizq of impendinn defa?cation A f t e r rectoplasty procedures when the only sphincter prerent was thc lcvntor ant complex, the ~inconrcioiis rrflexes were abolished. but the childreit attained approprmtc sensory perceptiolt and a high degree of continence provided that the rertiiiq tone of thc puborectalis muscle war adequate

Use of Anorectal Manometry for Objective Assessment of Anorectal Function After Pouch Ileoanal Anastomosis

“…The mechanism of continence depends on several factors including the function of anal sphincters [4].…”