https://www.nyp.org/healthlibrary/multimedia/anal-fissure-and-fistula
Anal Fissure And Fistula - Health Library | NewYork-Presbyterian
An anal fissure is a narrow tear that extends from the muscles that control the anus (sphincters) up into the anal canal. These tears usually develop when anal...
anal fissure and fistulahealth librarynewyorkpresbyterian