*The meninges are the coverings of the brain. They protect the brain by housing a fluid-filled space, and they function as a framework for blood vessels.
* The meninges have three layers: the dura mater, the arachnoid mater, and the pia mater. The arachnoid mater is attached to the pia mater by arachnoid trabeculae, which is a weblike matrix of connective tissue.
* The space between the two layers, the subarachnoid space, is filled with cerebrospinal fluid (CSF).
The subarachnoid space includes several cisterns, areas where the space between the pia and arachnoid mater is widened due to an accumulation of CSF, that function as reservoirs