APA Dictionary of Psychology

a type of herniation that occurs when increased intracranial pressure (resulting, e.g., from a tumor or head injury) displaces the medial temporal lobe or the deep hemisphere structures of the brain through the tentorial notch (an opening in the fold of dura mater that separates the cerebellum from the cerebrum). This causes displacement of the midbrain sideways and downward, which in turn may cause death. Also called tentorial herniation; uncal herniation.