parasympathetic nervous system

n. The portion of the autonomic nervous system that stimulates the smooth muscle systems in the body such as those in the digestive system and is associated with digestion, sleep and relaxation, sexual arousal and recuperation. It acts in a negatively reciprocal way with the sympathetic system, which prepares the body for large muscle activity as in the flight-or-fight syndrome. It includes the nerve fibers that leave the skull via the oculomotor, facial, glossopharyngeal, and vagus nerves, as well as the sacral nerves in the spinal cord.