meninges
35.3 | The Central Nervous System By the end of this section, you will be able to: Identify the spinal cord, cerebral lobes, and other brain areas on a diagram of the brain Describe the basic functions of the spinal cord, cerebral lobes, and other brain areas The central nervous system CNS is made up of the brain, a part of which is shown in Figure 35.19 and spinal cord and is covered with three layers of protective coverings called meninges from the Greek word for membrane . The outermost layer is the dura mater Latin for hard mother . As the Latin suggests, the primary function for this thick layer is to protect the brain and spinal cord. The dura mater also contains vein-like structures that carry blood from the brain back to the heart. The middle layer is the web-like arachnoid mater. The last layer is the pia mater Latin for soft mother , which directly contacts and covers the brain and spinal cord like plastic wrap. The space between the arachnoid and pia maters is filled with cerebrospinal fluid CSF . CSF is produced by a tissue called choroid plexus in fluid-filled compartments in the CNS called ventricles. The brain floats in CSF, which acts as a cushion and shock absorber and makes the brain neutrally buoyant. CSF also functions to circulate chemical substances throughout the brain and into the spinal cord.