Fissure
A cleft or groove.
A fissure can be normal or abnormal.
A fissure in the cerebral cortex is a normal feature.
It is a deep fold that involves the entire thickness of the brain wall.
A fissure in the anus is distinctly abnormal.
It is a painful crack in the edge of the anus and is very painful.
Also called an anal fissure or fissure in ano.