Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The arachnoid mater is one of the three protective membranes, known as the meninges, that surround the brain and spinal cord. It is located between the outermost layer, the dura mater, and the innermost layer, the pia mater.
Related terms
Dura Mater: The outermost and toughest layer of the meninges that provides a durable protective coating for the brain and spinal cord.
Pia Mater: The delicate innermost layer of the meninges that closely envelops the surface of the brain and spinal cord.
Cerebrospinal Fluid (CSF): A clear fluid found in and around the brain and spinal cord that acts as a cushion to protect these organs from injury