supratrochlear nerve

The supratrochlear nerve is a branch of the frontal nerve, itself a branch of the ophthalmic nerve (CN V1) from the trigeminal nerve (CN V). It provides sensory innervation to the skin of the forehead and the upper eyelid. Structure Origin The supratrochlear nerve is the smaller of the two terminal branches of the frontal nerve (the other being the supraorbital nerve). It arises midway between the base and apex of the orbit where the frontal nerve splits into said terminal branches. Course The supratrochlear nerve passes medially above the trochlea of the superior oblique muscle. It then travels anteriorly above the levator palpebrae superioris muscle. It exits the orbit through the supraorbital notch or foramen. It then ascends onto the forehead beneath the corrugator supercilii muscle and frontalis muscle. It finally divides into sensory branches.