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1. Anatomical definition - terminal part of GIT b/w dentate line & anal verge.
2. Anal margin - 5cm of skin surrounding anal verge.
3. Anal canal measures ~4cm long and is continuous with the rectum at the anorectal margin, which is the angle the rectum make at the levator ani.
4. Its muscular layer forms internal & external anal sphincters.
5. The dentate line spearates the canal into upper and lower parts based on structure and neurovascular supply. The dentate line is formed by a series of anal columns, which consist of a series of anal sinuses.
6. In the upper-part of the anal canal, the columnar epithelium gives way to stratified squamous epithelium at the squamo-columnar junction (generally corresponds to the dentate line).


1. Mcminn. (2003). Last's Anatomy. Elsevier Australia. ISBN:0729537528. Read it at Google Books - Find it at Amazon
2. Netter, F. H. (2019). Atlas of human anatomy. Philadelphia, PA: Elsevier.
3. Image: no reference available.

Ⓒ A. Manickam 2018

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