Which cranial nerve is responsible for supplying parasympathetic innervation to the lacrimal gland?

• A. CN II
• B. CN III
• C. CN VII
• D. CN X

Answer: (C)

Parasympathetic supply to the lacrimal gland comes from the facial nerve. Preganglionic fibers travel with the greater petrosal nerve and synapse in the pterygopalatine (pterygopalatine) ganglion. The postganglionic fibers then hitchhike with branches of the maxillary division of the trigeminal nerve, traveling in the zygomaticotemporal route to reach the lacrimal nerve and finally the lacrimal gland. This pathway explains why tearing is controlled by CN VII. Other nerves don’t innervate the lacrimal gland parasympathetically: the optic nerve is sensory for vision, the oculomotor nerve mainly supplies parasympathetic to the pupil/locus of lens but not lacrimal gland, and the vagus nerve supplies parasympathetic to thoracic and abdominal organs.