The meninges is the system of membranes which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater.
The pia mater is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord.
It is thin and mesh like and It supplies blood to the superficial areas of the cortex and supports larger blood vessels passing over the surface of the brain. The pia mater is anchored to the brain by the processes of astrocytes. It joins with the ependyma which lines the cerebral ventricles to form choroid plexuses that produce cerebrospinal fluid.
In the spinal cord, the pia mater attaches to the dura mater by denticulate ligaments that pass through the arachnoid mater.