Meninges – tough, moist membranes surrounding the brain and spinal cord. It consists of:Dura mater – tough outermost membrane (dm).
Arachnoid layer – a fibrous, delicate middle zone. Below this layer is the subarachnoid space filled with cerebrospinal fluid.
Pia mater – innermost of the meningeal layers. It is closely adherent to the surface of the brain and spinal cord.