English: The cerebroventricular system, along with the choroid plexuses and some feeding arteries. (a) CSF circulates through the four brain ventricles and in the subarachnoid space surrounding the brain and spinal cord. (b) View of the ventricular system along with the choroid plexus (CP) of the lateral (LV), 3rd and 4th ventricle. The arteries supplying these plexuses (not all are presented in the figure) are the anterior and lateral posterior choroidal arteries (ACA & LpCA), the P2 segment of the posterior cerebellar artery (PCA) and the medial posterior choroidal artery (MpCA) [12]. The MpCA arises from the PCA (or its branches) and enters the roof of the third ventricle [74] which feeds the CP situated there. Finally, the CP of the fourth ventricle is supplied by the posterior inferior cerebellar artery (PICA), inferior cerebellar artery (ICA) and superior cerebellar artery (SCA) [75]. ETV is the location of perforation of the floor of the third ventricle during endoscopic third ventriculostomy. [•] represents the locations of measurement for the deduction of the pressure difference between the lateral and fourth ventricles.