The choroid plexus of the fourth ventricle and its arteries.

The choroid plexus of the fourth ventricle consists of two symmetrical parts located in the roof of the ventricle and protruding through its openings, the foramina of Luschka and Magendie. The arteries supplying the choroid plexus of the fourth ventricle are difficult to approach because of their deep location within the cerebellopontine angles and the cerebellomedullary fissure. They originate from multiple sites on the cerebellar arteries, and pass near the vital structures of the pons and medulla. The increasing use of the operating microscope and endoscopy during operations in the posterior cranial fossa has created a need for better understanding of the microsurgical anatomy of the plexus and its arteries. The arteries of 15 human brain-stems with cerebelli were injected with coloured gelatine and fixed in 10% formaldehyde solution. The specimens were studied under an operating microscope. The choroids plexus on each side of the midline was divided into four segments, the medial and lateral horizontal segments and the rostral and caudal sagittal segments, in order to facilitate the description of their blood supply. The anterior inferior cerebellar artery (AICA), the posterior inferior cerebellar artery (PICA) and the superior cerebellar artery (SCA) were the main supplying vessels. AICA supplied the portion of the plexus in the cerebellopontine angles and the adjacent part of the lateral recess of the fourth ventricle through the foramina of Luschka. PICA supplied most of the choroid plexus in the roof and the median opening of the fourth ventricle.