Meninges refer to 3 layers that surround the spinal cord and brain. They are pia mater, arachnoid and dura mater. The 3 layers are there to protect the nerve system.
Pia mater. This is a very thin layer that covers the surface of the spinal cord and brain. Blood vessels go through it and connect with the spinal cord and brain.
Arachnoid. It's thin, transparent, and separated from the pia mater by the subarachnoid space. This part and the pia mater together are named the leptomeninges.
Dura mater. The layer is thick and strong. It covers the arachnoid. Its functions include supporting venous channels that send blood from your brain to the heart.