Figure 4.

Schematic adult brain with ventricular system with enlarged fourth ventricle inset illustrating formation of CSF. Red arrows indicate movement of filtrate from the venous system into the ventricles at the choroid plexus; Aqua arrows indicate movement of CSF through the ventricles to the subarachnoid space and central canal. Inset: Transverse section of medulla oblongata (myelencephalon) illustrating relationship of the choroid plexus epithelium invaginated into the CSF space of the fourth ventricle and the blood/brain barrier and compliance with CSF drainage.