(n.) The brain and spinal cord; the cerebro-spinal axis; myelencephalon.

afferent neuron autonomic nervous system axon brain central nervous system cerebral cortex craniosacral nervous system dendrite effector organ efferent neuron ganglion gray matter internuncial neuron medullary sheath nerve nerve trunk nervous system peripheral nervous system plexus sensorium sensory area sensory cell solar plexus spinal cord synapse thoracolumbar nervous system white matter