Pathology of the Gastrointestinal Tract

2017 Edition
| Editors: Fátima Carneiro, Paula Chaves, Arzu Ensari


  • Jean-François Fléjou
  • Denis Chatelain
Reference work entry


Anal canal


Classically, the generic term “anus” encompasses two parts: the anal canal and the anal margin or perianal skin. This terminology applies to the classification of anal tumors, which can be located either in the anal canal or in the anal margin. However, only the anal canal is precisely defined, and this term is often employed synonymously to the term anus.

The anus constitutes the distal 30–40 mm of the gastrointestinal tract. It extends from the rectum superiorly to the perianal skin inferiorly. The anal canal is defined surgically by the borders of the internal anal sphincter (Parks 1958). Anatomists use the levels of the anal valves and the anal orifice, respectively, to mark the upper and lower limits of the anus (Fenger 2007).

The mucosa comprises successive zones, with in the upper part vertical folds known as the anal columns, joined at their lower end by the anal valves marking the position of the dentate or pectinate line (see section “Microscopy”).

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References and Further Reading

  1. Fenger, C. (1988). Histology of the anal canal. The American Journal of Surgical Pathology, 12, 41–55.PubMedGoogle Scholar
  2. Fenger, C. (2007). Anal canal. In S. E. Mills (Ed.), Histology for pathologists (3rd ed., pp. 663–683). Philadelphia: Lippincott Williams & Wilkins.Google Scholar
  3. Nivatvongs, S., Stern, H. S., & Fryd, D. S. (1987). The length of the anal canal. Diseases of the Colon and Rectum, 24, 600–601.Google Scholar
  4. Parks, A. G. (1958). Modern concepts of the anatomy of the anal canal. Postgraduate Medical Journal, 34, 360–366.PubMedPubMedCentralGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Jean-François Fléjou
    • 1
  • Denis Chatelain
    • 2
  1. 1.Faculté de Médecine Pierre et Marie Curie, Service d’Anatomie et Cytologie PathologiquesHôpital Saint-AntoineParisFrance
  2. 2.Service d’Anatomie PathologiqueCentre Hospitalier et Universitaire du NordAmiensFrance