Central nervous system: only brain and spinal chord. Spinal chord: long, thin collection of nerve cells attached to base of brain and running along length of spinal column. Peripheral nervous system: cranial and spinal nerves; that part of the nervous system peripheral to brain and spinal chord. primarily control physiological functions and automatic behaviours. Cerebellum: pair of hemispheres resembling cerebral hemispheres but much smaller, lie beneath them, controls posture and movements, especially rapid ones. Cerebral hemispheres: largest part of brain, covered by cerebral cortex and containing parts of brain that evolved most recently. Meninges: 3-layered set of membranes that enclose the brain and spinal chord (protection due to pressure of evolution?) Cerebral spinal fluid (csf): liquid in which brain and spinal chord float, provides shock-absorbing cushion. brain does not come in direct contact with bones of skull and vertebrae. fills space between meninges, acts as shock absorber. Cerebral cortex: outer layer of cerebral hemispheres of brain.