The nasociliary nerve is a branch of the ophthalmic nerve, which is one of the three branches of the trigeminal nerve. Although there are no true synonyms for the nasociliary nerve, there are several terms that refer to its course, function, or neighboring structures. For example, the nasal nerve is a branch of the nasociliary nerve that innervates the nasal mucosa. The anterior ethmoidal nerve and posterior ethmoidal nerve are also branches of the nasociliary nerve that supply the ethmoid sinuses and parts of the meninges. Another term often used in conjunction with the nasociliary nerve is the ciliary ganglion, which is a small parasympathetic ganglion that lies just behind the eye socket and receives input from the nasociliary nerve.