Abstract
The role of the external and internal anal sphincters in the mechanism of anal continence is presented. The external sphincter induces continence by 1) preventing internal sphincter relaxation, what I have called the “voluntary inhibition action,” and 2) mechanical compression of the rectal neck and anal canal proper. The mechanism of both actions is described. The internal sphincter plays a significant role not only in involuntary, but also in voluntary, continence. The importance of this role in the correction of anal incontinence is clarified. “Stress defecation,” a condition which follows internal sphincter damage, is discussed. A “single loop continence” theory is presented, based on the fact that each of the three loops of the external sphincter has its own innervation, attachment, and direction of muscle bundles; each loop thus acts as a separate sphincter. The clinical application of this theory is presented.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Shafik A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. I. The external anal sphincter. A triple-loop system. Invest Urol 1975;12:412.
Shafik A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. II. Anatomy of the levator ani muscle with special reference to puborectalis. Invest Urol 1975;13:175.
Shafik A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. III. The longitudinal anal muscle: Anatomy and role in anal sphincter mechanism. Invest Urol 1976;13:271.
Shafik A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. IV. Anatomy of the perianal space. Invest Urol 1976;13:424.
Shafik A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. V. The rectal neck. Anatomy and function. Chir Gastroenterol (Surg Gastroenterol) 1977;11:319.
Goodsall DH, Miles WE. Diseases of the anus and rectum. London: Longmans, Green & Co., Part 1, 1900-05.
Allingham W, Allingham HW. The diagnosis and treatment of diseases of the rectum; being a practical treatise on fistula, piles, fissure and painful ulcer, procidentia, polypus, stricture, cancer, etc. London: Bailliere, Tindall and Cox, 1901.
Tuttle JP. A treatise on diseases of the anus, rectum and pelvic colon. New York: Appleton, 1902.
Lockhart-Mummery JP. Diseases of the rectum and colon and their surgical treatment. 2nd ed. Baltimore: William Wood, 1934.
Goligher JC. Surgery of the anus, rectum and colon. 3rd ed. London: Bailliere Tindall, 1975: 15, 17,225.
Milligan ET, Morgan CN. Surgical anatomy of the anal canal with special reference to anorectal fistulae. Lancet 1934;2:1150–1213.
Gaston EA. The physiology of fecal continence. Surg Gynecol Obstet 1948;87:280.
Garry RC. The repsonses to stimulation of the caudal end of the large bowel in the cat. J Physiol 1933;78:208.
Bennett RC, Goligher JC. Results of internal sphincterotomy for anal fissure. Br Med J 1962;2:1500.
Parks AG, McPartlin JF. Late repair of injuries of the anal sphincter. Proc R Soc Med 1971;64:1187.
Mann A. Gracilis anoplasty: report of a successful case. Aust NZ J Surg 1970;39:405.
Caldwell KP. A new treatment of rectal prolapse. Proc R Soc Med 1965;58:792.
Author information
Authors and Affiliations
About this article
Cite this article
Shafik, A. A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. Dis Colon Rectum 23, 37–43 (1980). https://doi.org/10.1007/BF02587198
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02587198