lacrimal nerve

The lacrimal nerve is a branch of the ophthalmic nerve, which itself is one of the three major branches of the trigeminal nerve (CN V). The trigeminal nerve is the largest cranial nerve and has both sensory and motor functions. The ophthalmic nerve enters the orbit and then divides into several branches, including the lacrimal nerve.1

The lacrimal nerve primarily serves the lacrimal gland, which produces tears. It also supplies a portion of the upper eyelid and the conjunctiva, the membrane lining the eyelid and covering the white part of the eye. Tears are essential for keeping the eye surface moist, providing nutrition and oxygen, and possessing antibacterial properties. The lacrimal apparatus includes the main lacrimal glands and accessory glands, which secrete tears that drain through small openings called puncta into the lacrimal sacs and then into the nasal cavity.123