The greater petrosal nerve, which carries sensory fibers as well as preganglionic parasympathetic fibers, emerges from the anterior aspect of the ganglion.
It may be either organic, through stimulation of the parasympathetic nervous system, or functional in origin, through eye strain or fatigue of ocular systems.
The mucous membranes receive their postganglionic parasympathetic nerve innervation for mucous secretion originating from the greater petrosal nerve (a branch of the facial nerve).
This is accomplished by the brain reflexively withdrawing the parasympathetic nerve signals and increasing the sympathetic nerve signals it sends to the heart.
Scopolamine and hyoscyamine are the most widely used tropane alkaloids in pharmacology and medicine due to their effects on the parasympathetic nervous system.