The meninges (singular meninx)'s the system of membranes which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid's to protect the central nervous system. Anatomy Dura mater The dura mater (also rarely called meninx fibrosa, or pachymeninx)'s a thick, durable membrane, closest to the skull. It consists of two layers, the periosteal layer, closest to… (More on Meninges)