part of part of location of adjacent to anatomical space cerebrospinal fluid blood vessel pia mater meningeal cluster perivascular space VRS belonging to the subarachnoid space are continuous with VRS of the subpial space. The direct communication between VRS of the subarachnoid space and the subpial space is unique to the brain's arteries, as no leptomeningeal layers surround the brain's veins[WP]