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Anal Physiology: The Physiology of Continence and Defecation

  • Vitaliy Poylin
  • Thomas E. CataldoEmail author
Chapter

Abstract

The physiology of the anus and its surrounding structures is the physiology of continence and controlled defecation. This is a physiology of balance and continuous feedback and complex reflexes. Continence requires balance between the pressure inside the rectum and the combined tone of the internal and external sphincters. This chapter provides an overview of the anatomy, specifically the innervation of the anal complex with regard to how it affects normal and pathologic defecation. The neuro-sensory-motor aspects of the sequences of events of defecation are reviewed. Conditions that result in disordered defecation, pelvic pain, and complications outside the GI system are discussed.

Keywords

Physiology Anorectal innervation Defecation Continence Pelvic floor RAIR Anorectal pain Obstructed defecation 

Abbreviations

RAIR

Rectoanal inhibitory reflex

SNS

Sacral nerve stimulation

FI

Fecal incontinence

MR

Magnetic resonance

Supplementary material

Video 3.1

Normal defecography (Courtesy of Shauna Lorenzo-Rivero, MD, FACS, FASCRS) (WMV 1122 kb)

Video 3.2

Defeocography of a patient with a rectocele (Shauna Lorenzo-Rivero, MD, FACS, FASCRS) (WMV 723 kb)

References

  1. 1.
    Jorge JMN, Habr-Gama A. Anatomy and embryology of the colon rectum and anus. In: Wolff BG, Fleshman JW, Beck DE, Pemberton JH, Wexner SD, editors. The ASCRS textbook of colon and rectal surgery. New York, NY: Springer; 2007. p. 1–11.Google Scholar
  2. 2.
    Bollard RC, Gardiner A, Lindow S, Phillips K, Duthie GS. Normal female anal sphincter: difficulties in interpretation explained. Dis Colon Rectum. 2002;45:171–5.CrossRefGoogle Scholar
  3. 3.
    Gordon PH. Anatomy and physiology of the anorectum. In: Fazio VW, Church JM, Delaney CP, editors. Current therapy in colon and rectal surgery. 2nd ed. Philadelphia, PA: Elsevier Mosby; 2005. p. 1–4.Google Scholar
  4. 4.
    Milligan ETC, Morgan CN, Jones LE, Officer R. Surgical anatomy of the anal canal and the operative treatment of haemorrhoids. Dis Colon Rectum. 1985;28:620–8.CrossRefGoogle Scholar
  5. 5.
    Morgan CN. The surgical anatomy of the anal canal and rectum. Postgrad Med J. 1936;12:287–314.CrossRefGoogle Scholar
  6. 6.
    Taylor I, Duthie HL, Amallwwod R, et al. Large bowel myoelectrical activity in man. Gut. 1975;16:808–14.CrossRefGoogle Scholar
  7. 7.
    Gordon PH. Anorectal anatomy and physiology. Gastroenterol Clin North Am. 2001;30:1–13.CrossRefGoogle Scholar
  8. 8.
    Gowers WR. The automatic action of the sphincter ani. Proc R Soc Lond. 1877;26:77–84.CrossRefGoogle Scholar
  9. 9.
    Cornes H, Bartolo DCC, Stirra T. Changes in anal canal sensation after childbirth. Br J Surg. 1991;78:74–7.CrossRefGoogle Scholar
  10. 10.
    Miller R, Bartolo DCC, Cervero F, Mortenson NJ. Differences in anal sensation in continent and incontinent patients with perineal descent. Int J Colorectal Dis. 1989;4:45–9.CrossRefGoogle Scholar
  11. 11.
    Keighley MRB. Abdominal mucosectomy reduces the incidence of soiling and sphincter damage after restorative proctocolectomy and J-pouch. Dis Colon Rectum. 1987;39:386–90.CrossRefGoogle Scholar
  12. 12.
    Stelzner F. The morphological principles of anorectal continence. In: Rickham PP, Hecker WSH, Prevot J, editors. Anorectal malformations and associated diseases, Progress in pediatric surgery series, vol. 9. Munich: Urban & Schwarzberg; 1976. p. 1–6.Google Scholar
  13. 13.
    Kaiser AM, Ortega AE. Anorectal anatomy. Surg Clin North Am. 2002;82:1125–38.CrossRefGoogle Scholar
  14. 14.
    Duthie HL, Gairns FW. Sensory nerve-endings and sensation in the anal region of man. Br J Surg. 1960;206:585–95.CrossRefGoogle Scholar
  15. 15.
    Sangwan YP, Solla JA. Internal anal sphincter: advances and insights. Dis Colon Rectum. 1998;41:1297–311.CrossRefGoogle Scholar
  16. 16.
    Palit S, Lunniss PJ, Scott SM. The physiology of human defecation. Dig Dis Sci. 2012;57:1445–64.CrossRefGoogle Scholar
  17. 17.
    Bajwa A, Emmanuel A. The physiology of continence and evacuation. Best Pract Res Clin Gastroenterol. 2009;23:477–85.CrossRefGoogle Scholar
  18. 18.
    Brookes SJ, Dinning PG, Gladman MA. Neuroanatomy and physiology of colorectal function and defaecation: from basic science to human clinical studies. Neurogastroenterol Motil. 2009;21 Suppl 2:9–19.CrossRefGoogle Scholar
  19. 19.
    Gurjar SV, Jones OM. Physiology: evacuation, pelvic floor and continence mechanisms. Surgery. 2011;29(8):358–61.Google Scholar
  20. 20.
    Lubowski DZ, Meagher AP, Smart AC, et al. Scintographic assessment of colonic function during defecation. Int J Colorectal Dis. 1995;10:91–3.CrossRefGoogle Scholar
  21. 21.
    Brading AF, Ramalingam T. Mechanisms controlling normal defecation and the potential effects of spinal cord injury. In: Weaver LC, Polosa C, editors. Progress in brain research 2006; vol 152:p. 345-358 (Chapter 23).CrossRefGoogle Scholar
  22. 22.
    Broens PMA, Penninckx FM, Ochoa JB. Fecal continence revisited: the anal external sphincter continence reflex. Dis Colon Rectum. 2013;56:1273–81.CrossRefGoogle Scholar
  23. 23.
    Lynn PA, Olsson C, Zagorodnyuk V, et al. Rectal intraganglionic laminar endings are transduction sites of extrinsic mechanoreceptors in the guinea pig rectum. Gastroenterology. 2003;125:589–601.CrossRefGoogle Scholar
  24. 24.
    Lynn PA, Blackshaw LA. In vitro recordings of afferent fibres with receptive fields in the serosa, muscle and mucosa of rat colon. J Physiol. 1999;518(Pt 1):271–82.CrossRefGoogle Scholar
  25. 25.
    Tanagho EA, Schmidt RA. Electrical stimulation in the clinical management of the neurogenic bladder. J Urol. 1988;140:1331–9.CrossRefGoogle Scholar
  26. 26.
    Ganio E, Luc AR, Clerico G, Trompetto M. Sacral nerve stimulation for treatment of fecal incontinence: a novel approach for intractable fecal incontinence. Dis Colon Rectum. 2001;44:619–29.CrossRefGoogle Scholar
  27. 27.
    Malouf AJ, Wiesel PH, Nicholls T, Nicholls RJ, Kamm MA. Sacral nerve stimulation for idiopathic slow transit constipation. Gastroenterol Clin North Am. 2001;118:4448–9.Google Scholar
  28. 28.
    Carrington EV et al. A systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation. Neurogastroenterol Motil. 2014;26(9):1222–37.CrossRefGoogle Scholar
  29. 29.
    Thumas TO, Dudding TC, et al. A systemic review of posterior tibial nerve stimulation for faecal incontinence. Colorectal Dis. 2012;15:519–26.CrossRefGoogle Scholar
  30. 30.
    Ebert E. Gastrointestinal involvement in spinal cord injury: a clinical perspective. J Gastrointestin Liver Dis. 2012;21(1):75–82.PubMedGoogle Scholar
  31. 31.
    Lynch AC, Frizelle FA. Colorectal motility and defecation after spinal cord injury in humans. In: Weaver LC, Polosa C, editors. Progress in brain research 2006;vol 152:193–203 (Chapter 23).Google Scholar
  32. 32.
    Nout YS, Leedy GM, Beattie MS, Bresnahan JS. Alterations in eliminative and sexual reflexes after spinal cord injury: defecatory function and development of spasticity in pelvic floor musculature. In: Weaver LC, Polosa C, editors. Progress in brain research 2006;vol 152:359–273 (Chapter 23).CrossRefGoogle Scholar
  33. 33.
    Preziosi G, Raptis DA, Raeburn A, Panicker J, Emmanuel A. Autonomic rectal dysfunction in patients with multiple sclerosis and bowel symptoms is secondary to spinal cord disease. Dis Colon Rectum. 2014;57:514–21.CrossRefGoogle Scholar
  34. 34.
    Valle’s M, Mearin F. Pathophysiology of bowel dysfunction in patients with motor incomplete spinal cord injury: comparison with patients with motor complete spinal cord injury. Dis Colon Rectum. 2009;52:1589–97.CrossRefGoogle Scholar
  35. 35.
    Bharucha AE, Rao SSC. An update on anorectal disorders for gastroenterologists. Gastroenterology. 2014;146:37–45.CrossRefGoogle Scholar
  36. 36.
    Bharucha AE, Wald A, Enck P, Rao S. Functional anorectal disorders. Gastroenterology. 2006;130:1510–8.CrossRefGoogle Scholar
  37. 37.
    van Ginkel R, Reitsma JB, Buller HA, et al. Childhood constipation: longitudinal follow-up beyond puberty. Gastroenterology. 2003;125:67–72.Google Scholar
  38. 38.
    Rao SSC, Tuteja AK, Vellema T, et al. Dyssynergic defecation: demographics, symptoms, stool patterns and quality of life. J Clin Gastroenterol. 2004;38:680–5.CrossRefGoogle Scholar
  39. 39.
    Rao SS, Welcher KD, Leistikow JS. Obstructive defecation: a failure of rectoanal coordination. Am J Gastroenterol. 1998;93:1042–50.CrossRefGoogle Scholar
  40. 40.
    Andromanakos N, Skandalakis P, Troupis T, Filippou D. Constipation of anorectal outlet obstruction: pathophysiology, evaluation and management. J Gastroenterol Hepatol. 2006;21:638–46.CrossRefGoogle Scholar
  41. 41.
    Felt-Bersma RJ, Tiersma ES, Cuesta MA. Rectal prolapse, rectal intussusception, rectocele, solitary rectal ulcer syndrome, and enterocele. Gastroenterol Clin North Am. 2008;37:645–68.CrossRefGoogle Scholar
  42. 42.
    Atkin GK, Suliman A, Vaizey CJ. Patient characteristics and treatment outcome in functional anorectal pain. Dis Colon Rectum. 2011;54:870–5.CrossRefGoogle Scholar
  43. 43.
    Hull M, Cort MM. Evaluation of the levator ani and pelvic wall muscles in levator ani syndrome. Urol Nus. 2009;29(4):225.Google Scholar
  44. 44.
    Eckardt VF, Dodt O, Kanzler G, Bernhard G. Anorectal function and morphology in patients with sporadic proctalgia fugax. Dis Colon Rectum. 2004;39:755–62.CrossRefGoogle Scholar
  45. 45.
    Shin GH, Toto EL, Schey R. Pregnancy and postpartum bowel changes: constipation and fecal incontinence. Am J Gastroenterol. 2015;110:521–9.CrossRefGoogle Scholar
  46. 46.
    Chiloiro M, Darconza G, Piccioli E, et al. Gastric emptying and orocecal transit time in pregnancy. J Gastroenterol. 2001;36:538–43.CrossRefGoogle Scholar
  47. 47.
    Oettling G, Franz HB. Mapping of androgen, estrogen and progesterone receptors in the anal continence organ. Eur J Obstet Gynecol Reprod Biol. 1998;77:785–95.CrossRefGoogle Scholar
  48. 48.
    Shultz SJ, Wideman L, Montgomery MM, et al. Changes in serum collagen markers, IGF-I, and knee joint laxity across the menstrual cycle. J Orthop Res. 2012;30:1405–12.CrossRefGoogle Scholar
  49. 49.
    Parks AG, Swash M. Denervation of the anal sphincter causing idiopathic anorectal incontinence. J R Coll Surg Edinb. 1979;24:94–6.PubMedGoogle Scholar
  50. 50.
    Bharucha AE, Fletcher JG, Melton III LJ, et al. Obstetric trauma, pelvic floor injury and fecal incontinence: a population-based case–control study. Am J Gastroenterol. 2012;107:902–11.CrossRefGoogle Scholar
  51. 51.
    Dudding TC, Vaizey CJ, Kamm MJ. Obstetric anal sphincter injury incidence, risk factors, and management. Ann Surg. 2008;247(2):224–37.CrossRefGoogle Scholar
  52. 52.
    Pretlove SJ, Thompson PJ, Toozs-Hobson PM, et al. Does the mode of delivery predispose women to anal incontinence in the first year postpartum? A comparative systematic review. BJOG. 2008;115:421–34.CrossRefGoogle Scholar

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© ASCRS (American Society of Colon and Rectal Surgeons) 2016

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Authors and Affiliations

  1. 1.Dept of Surgery, Division of Colon and Rectal Surgery etcBeth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUSA
  2. 2.Dept of Surgery, Division of Colon and Rectal Surgery etcBeth Israel Deaconess Medical Center, Harvard Medical SchoolBostonUSA

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