Subarachnoid space

In the central nervous system, the subarachnoid space (subarachnoid cavity) is the anatomic space between the arachnoid mater and the pia mater.

It is occupied by spongy tissue consisting of trabeculae (delicate connective tissue filaments that extend from the arachnoid mater and blend into the pia mater) and intercommunicating channels in which the cerebrospinal fluid is contained.