Structure and Origin - The supratrochlear nerve is a terminal branch of the frontal nerve. - It arises midway between the base and apex of the orbit. - The supratrochlear nerve passes above the trochlea of the superior oblique muscle. - It travels anteriorly above the levator palpebrae superioris muscle. - The nerve exits the orbit through the supraorbital notch or foramen.

Course - The supratrochlear nerve passes medially above the trochlea of the superior oblique muscle. - It then travels anteriorly above the levator palpebrae superioris muscle. - Exiting the orbit through the supraorbital notch or foramen. - It ascends onto the forehead beneath the corrugator supercilii muscle and frontalis muscle. - Finally, it divides into sensory branches.

Function - The supratrochlear nerve provides sensory innervation to the skin and conjunctiva of the upper eyelid. - It also innervates the skin of the inferomedial forehead. - The nerve may provide sensory innervation to part of the periosteum of the frontal bone.

Clinical Significance - The supratrochlear nerve can be anesthetised for surgery of parts of the scalp. - It is used for small lesions or more extensive injuries to the scalp. - Often, the nerve is anesthetised alongside the supraorbital artery.

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