Brain membranes and anatomy. Illustration of the anatomy of the meninges, the membranes that enclose the brain (pink). The outer layers above the membranes are the skull (grey), the periosteum, and an outer skin layer (pink) that includes scalp hairs. From outer to inner, the three meninges are the dura mater (a double layer, pink), the arachnoid mater (grey), and the pia mater (pink, on surface of brain). The two dura mater layers are the superficial endosteal layer and the inner meningeal layer. The space between the pia mater and arachnoid mater (the subarachnoid space) contains cerebrospinal fluid and filaments called arachnoid trabeculae. Also shown are arterial (red) and venous (blue) capillaries, part of the blood-brain barrier. |