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Frontal Nerve

nervus frontalis

The frontal nerve is the largest branch of the ophthalmic division of the trigeminal nerve (V1). It enters the orbit through the superior orbital fissure above the annulus of Zinn and runs forward along the roof of the orbit between the periorbita and the levator palpebrae superioris. Just before the orbital rim it divides into the supraorbital nerve (which exits through the supraorbital notch or foramen) and the supratrochlear nerve (which exits above the trochlea of the superior oblique). Both provide cutaneous sensation to the forehead and anterior scalp.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The frontal nerve is anaesthetised by superior orbital nerve block, providing forehead anaesthesia for forehead laceration repair, frontal sinus procedures, and scalp surgery. Herpes zoster affecting V1 (zoster ophthalmicus) preferentially affects the frontal nerve, producing vesicular eruption over the forehead and scalp. Compression of the frontal nerve within the superior orbital fissure contributes to orbital apex syndrome. The nerve's two terminal branches (supraorbital and supratrochlear) are individually named and are already well-documented landmarks.

Pathology

Common Injuries & Conditions

Superior Orbital Fissure Syndrome

Compression of the frontal nerve along with CN III, IV, VI, and the other V1 branches within the superior orbital fissure from trauma, tumour, or inflammation produces orbital pain, forehead numbness, ophthalmoplegia, and ptosis without proptosis, distinguishing it from orbital apex syndrome which also involves the optic nerve.