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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