#rectum  the terminal section of the alimentary canal; from the sigmoid flexure to the anus
  supertype:  body_part  any part of an organism such as an organ or extremity
  part of:  large_intestine
  part:  rectal_artery__arteria_rectalis  one of the arteries supplying the rectal area
  part:  anus__arse__arsehole__asshole  excretory opening at the end of the alimentary canal
     part:  anal_sphincter__sphincter_ani__sphincterani__musculus_sphincter_ani  the sphincter muscle of the anus
        part:  musculus_sphincter_ani_externus  an external ring of striated muscle surrounding the anus
        part:  musculus_sphincter_ani_internus  an internal ring of smooth muscle formed by circular fibers of the rectum

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