Ophthalmic nerve

At a glance

English

Ophthalmic nerve

Latin (TA2)

Nervus ophthalmicus

System

Nerve

Region

Head

Side

Paired, left and right

About the ophthalmic nerve

The ophthalmic nerve, V1, is the uppermost and smallest trigeminal division. It is purely sensory. Its territory runs from the eye itself, including the cornea, through the upper eyelid, eyebrow and forehead back across the scalp to about the vertex, together with the bridge and tip of the nose and the lining of the front of the nasal cavity and nearby air sinuses.

It sets out from the top of the trigeminal ganglion, a flat band roughly 2.5 cm long. It runs forwards in the outer wall of the cavernous sinus, beneath nerves III and IV and beside the abducens nerve. Here it receives sympathetic filaments from the plexus around the internal carotid artery, exchanges fibres with the three nerves that move the eye, and gives a small recurrent branch that turns back into the tentorium cerebelli. Just before reaching the superior orbital fissure it splits into three branches, which enter the orbit.

The lacrimal nerve, the smallest, runs along the upper border of lateral rectus to the lacrimal gland and the outer part of the upper lid; on the way it receives secretory fibres for the gland from the zygomatic nerve. The frontal nerve, the largest, runs forward on levator palpebrae superioris and splits into the supraorbital nerve, which leaves through the supraorbital notch or foramen to the forehead and scalp, and the smaller supratrochlear nerve to the medial forehead. The nasociliary nerve passes medially across the optic nerve and gives a branch to the ciliary ganglion, the long ciliary nerves to the eyeball and the anterior and posterior ethmoidal nerves to the sinuses and nasal cavity; it ends as the infratrochlear nerve, while its anterior ethmoidal branch reappears on the nose as the external nasal nerve.

Its fibres from the cornea form the sensory side of the blink (corneal) reflex. If the nerve is damaged, the cornea becomes numb, the reflex is lost and the eye is at risk of unnoticed injury and ulcers. Shingles in this division, herpes zoster ophthalmicus, causes a painful rash over the forehead; a rash on the tip of the nose (Hutchinson's sign) shows the nasociliary nerve is involved and warns that the eye itself may be affected.

Course and supply

Arises from

The top of the trigeminal ganglion in the middle cranial fossa; it runs forward in the outer wall of the cavernous sinus.

Ends in

Divides just before the superior orbital fissure into the lacrimal, frontal and nasociliary nerves.

Supplies

Sensory to the eyeball and cornea, conjunctiva, lacrimal gland, upper eyelid, forehead, scalp to the vertex, nose, frontal and ethmoidal sinuses, and dura of the anterior cranial fossa and tentorium.