The choroidal fissure, or choroid fissure, is a cleft of the medial surface of the cerebral hemisphere running immediately above the hippocampus and forms the medial wall of the lateral ventricle and attachment site for the choroid plexus.
The C-shaped fissure runs between the fornix (body, crus, and fimbria) and the thalamus. At the level of the hippocampus, the choroidal fissure is a lateral extension of the transverse fissure of Bichat, which in turn is a lateral extension of the ambient cistern .
The choroid plexus originates at the inferior choroidal point of the choroidal fissure, which is located just posterior to the hippocampal head. At this location, the anterior choroidal artery enters the temporal horn of the lateral ventricle. Only choroid plexus and a thin arachnoid membrane separate the cerebrospinal fluid space of the choroidal fissure and the lateral ventricle.