PANCE Gastrointestinal (GI) and Nutrition Practice Test

Most anal fissures occur in the posterior midline of the anal canal. This area sits in a watershed zone with relatively limited blood supply, making the mucosa more prone to tearing during stool passage, especially with constipation and straining. The pain is typically sharp because the fissure is distal to the dentate line, where somatic nerves provide strong pain sensation. Anterior midline fissures are much less common, and fissures at the lateral margins suggest an underlying condition such as Crohn disease or infection, rather than a simple fissure.