The dura mater is the thickest and most external of the coverings.
The arachnoid mater is against the internal surface of the dura mater.
The pia mater is adherent to the brain and spinal cord.
Between the arachnoid and pia mater is the subarachnoid space, which contains CSF.
A further discussion of the cranial meninges can be found in Chapter 8 and of the spinal meninges in Chapter 2.
Functional subdivisions of the CNS