Which layer of the meninges lies between the dura mater and the pia mater?

The layer of the meninges that lies between the dura mater and the pia mater is the arachnoid mater. The meninges consist of three protective membranes surrounding the brain and spinal cord: the dura mater, the arachnoid mater, and the pia mater.

The dura mater is the outermost layer, providing a tough protective covering, while the pia mater is the innermost layer that closely adheres to the surface of the brain and spinal cord. The arachnoid mater is situated in the middle, serving as a cushioning layer that can also help regulate the flow of cerebrospinal fluid (CSF) between the brain and the surrounding environment. This positioning allows the arachnoid mater to form a subarachnoid space beneath it, where CSF circulates, providing further protection and support to the central nervous system.

In summary, understanding these layers and their arrangement is crucial for comprehending the protective structures of the central nervous system, making the arachnoid mater the correct answer in this context.