The meninges are the membranes that surround and protect the brain and the spinal cord. In mammals, the meninges have three layers: the dura mater, the arachnoid mater, and the pia mater.[1]
In the space between the arachnoid mater and the pia mater (called the "subarachnoid space"), there is cerebrospinal fluid (CSF). CSF is a special fluid which bathes the brain and spinal cord. The meninges and the CSF work together to cushion and protect the central nervous system (the brain and spinal cord).[1]