Ask the Chatbot Games & Quizzes ProCon History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture Money Videos
anal canal
Discover
Super Typhoon Noru over the western tropical Pacific Ocean as observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA Aqua satellite July 31 2017
What Is the Difference Between a Typhoon and a Super Typhoon?
Wolfgang Amadeus Mozart. Mozart rehearsing his 12th Mass with singer and musician. (Austrian composer. (Johann Chrysostom Wolfgang Amadeus Mozart)
7 Famous Child Prodigies
Close-up of tobacco plants in Ontario, Canada. Tobacco, Nicotiana, cured leaves used after processing in various ways for smoking, snuffing, chewing, and extracting of nicotine.
7 of the World’s Deadliest Plants
New York NY/ USA- November 23, 2018 Hordes of shoppers throng the Macy's Herald Square flagship store in New York looking for bargains on the day after Thanksgiving, Black Friday.
Why Is It Called Black Friday?
A human Inuit skull in a stone chambered cairn in Ilulissat in Greenland. These ancient graves are pre christian and are at least 2000
14 Tough Questions Answered
Nero (Nero Claudius Caesar Augustus Germanicus) (ad 50-54) the fifth Roman emperor (ad 54-68), stepson and heir of the emperor Claudius.
Did Nero Really Fiddle as Rome Burned?
Black widow spider
9 of the World’s Deadliest Spiders
anal canal Article

anal canal summary

Know about the structure and function of the anal canal

verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Share
Share to social media
URL
https://www.britannica.com/summary/anal-canal
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
Written and fact-checked by
The Editors of Encyclopaedia Britannica
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.
The Editors of Encyclopaedia Britannica
Below is the article summary. For the full article, see anal canal.

anal canal, End portion of the alimentary canal, distinguished from the rectum by the transition from an internal mucous membrane layer to one of skinlike tissue and by its narrower diameter. Waste products move from the rectum to the anal canal. The human anal canal is 1–1.5 in. (2.5–4 cm) long and has three parts: upper, with longitudinal folds (rectal columns); lower, with involuntary and voluntary constrictive muscles (sphincters) to control discharge of feces; and the anal opening itself. Enlargements of the ends of rectal and anal veins are called hemorrhoids.