What is the middle layer of the protective coverings of the centeral nervous system?

The middle layer of the protective coverings of the central nervous system is called the arachnoid mater. It is one of three meninges, situated between the outer dura mater and the inner pia mater. The arachnoid mater is a delicate, web-like membrane that helps protect the brain and spinal cord, as well as providing a space for cerebrospinal fluid (CSF) to circulate, which cushions and nourishes the central nervous system.