Definition The autonomic nervous system is made up of 2 subdivisions: sympathetic and parasympathetic systems. The sympathetic system originates from the thoracolumbar regions (T1-L2) of the spinal cord. The parasympathetic system originates from craniosacral regions (brainstem nuclei CN III, VII, IX, and X as well as sacral levels S2-S4). In general, there are 2 neurons […]