Introduction:
Both divisions of the autonomic nervous system are found innervating certain structures in the head.
In general, the sympathetic nervous system continues its primary task of innervating vascular smooth muscle, along with sweat glands and arrector pili muscles. Sympathetics in the head also innervate a muscle that helps to elevate the upper eyelid (superior tarsal muscle) and the muscle that dilates the pupil (dilator pupillae).
The parasympathetic nervous system in the head continues to innervate mucous glands as elsewhere in the body. It also innervates the 3 pairs of salivary glands, the lacrimal gland (for tears), and 2 muscles of the eyeball - the sphincter pupillae and the ciliary muscle (for accommodation or close-up viewing).
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