The pia mater is the innermost layer of the three protective membranes, known as the meninges, that surround the brain and spinal cord. It is a delicate, thin membrane that closely adheres to the surface of the brain, following its contours and grooves. The pia mater contains blood vessels that supply nutrients to the brain and spinal cord. This layer plays a crucial role in protecting the central nervous system. It helps to maintain the stability of the brain's environment and supports the overall function of the central nervous system. The pia mater works in conjunction with the other meninges, the arachnoid mater and the dura mater, to provide comprehensive protection.