Sagittal view of right cerebrum and ventricular system. Choroid plexi located within each of the ventricles are comprised of ependymal cells that produce cerebral spinal fluid (CSF). Paired lateral ventricles are c-shaped structures that extend through the temporal, parietal, and frontal lobes. CSF passes from the lateral ventricles into the 3rd ventricle through the interventricular foramina (of Monro). CSF from the 3rd ventricle drains inferiorly to the 4th ventricle through the cerebral aqueduct. The medial posterior choroidal arteries are branches of the posterior cerebral artery (PCA) that supply the choroid plexus of the 3rd ventricle. (Image courtesy of AL Rhoton, Jr.)