In the cranial region, visceral components are associated with four of the twelve cranial nerves (CN III, VII, IX, and X).
In the spinal cord, visceral components are associated mainly with spinal cord levels T1 to L2 and S2 to S4.
Visceral motor components associated with spinal levels T1 to L2 are termed sympathetic. Those visceral motor components in cranial and sacral regions, on either side of the sympathetic region, are termed parasympathetic: