Microsurgical anatomy of the choroidal arteries. Fourth ventricle and cerebellopontine angles.

The microsurgical anatomy of the arteries supplying the choroid plexus in the fourth ventricle and cerebellopontine angles was examined under X3 to X20 magnification in brains from 25 adult cadavers. In the most common pattern, the branches of the anterior inferior cerebellar artery (AICA) supplied the portion of the choroid plexus in the cerebellopontine angle and adjacent part of the lateral recess of the fourth ventricle, and the posterior inferior cerebellar artery (PICA) supplied the choroid plexus in the roof and medial part of the lateral recess of the fourth ventricle. The superior cerebellar artery (SCA) gave rise to a choroidal branch in only one brain. The choroid plexus on each side of the midline was divided into a medial and a lateral segment. Each segment was considered two parts to facilitate the description of its blood supply. The medial segment, located in the roof of the fourth ventricle, was divided into a rostral or nodular part, and a caudal or tonsillar part. The lateral segment, located in the lateral recess of the fourth ventricle and cerebellopontine angle, was separated into a medial or peduncular part, and a lateral or floccular part. The AICA most commonly supplied all the floccular part and the lateral portion of the peduncular part, and the PICA most commonly supplied all of the tonsilar and nodular parts, and the medial portion of the peduncular part.