Trigeminal nerve (part-2) - Ophthalmic division course, distribution, branches.

 Abstract:

Ophthalmic division is first branch of trigeminal nerve. Purely sensory in nature. Travels anteriorly in lateral wall of cavernous sinus to the medial part of superior orbital fissure, through which it exits the skull into the orbit. Before passing through superior orbital fissure it divides into three branches- lacrimal, frontal, nasociliary.

Course & Relation:

Arises - medial part of convex anterior border of the trigeminal ganglion.

Pierces- duramater of trigeminal cave.

Enters- lateral wall of cavernous sinus, where it lies below trochlear nerve.

            

Enters orbit through superior orbital fissure by dividing into 3 branches:

Branches:

Lacrimal branch: 

Course- runs along lateral wall of the orbit along with lacrimal artery and end in lacrimal gland.

Supplies- lacrimal gland & conjunctiva.

Pierces- orbital septum to supply the lateral part of skin of upper eyelid.

Frontal branch:

Course:- runs forward between levator palpebral superioris and periosteum lining the roof of the orbit.

In middle of orbit it divides into - large supraorbital & small supratrochlear nerve.

👉 Supraorbital nerve:  Frontal air sinus, upper eyelid, forehead, scalp till vertex.

👉Supratrochlear nerve: upper eyelid, conjunctiva, lower part of forehead.

Nasociliary branch:

💨 Runs forward and medially crossing optic nerve from above.

💨 Runs from lateral to medial side behind the ophthalmic artery.

💨 On reaching the medial wall of the orbit, it ends by dividing into anterior ethmoidal and infratrochlear nerves.

Branches:

a)Anterior ethmoidal nerve: supplies- middle and anterior ethmoidal sinus, medial internal nasal, lateral internal nasal, external nasal- skin of ala of vestibule and tip of nose.

Course of anterior ethmoidal nerve:

In nasal cavity- it lies in groove on posterior surface of nasal bone, gives internal nasal branches to nasal septum & lateral wall of nose.

At lower border of nasal bone, the nerve leaves nasal cavity & appears on dorsum of nose as external nasal nerve.

b)Infratrochlear nerve: both eyelid, side of nose, lacrimal sac.

c) Sensory root to ciliary ganglion- given just before crossing optic nerve.

d) Long ciliary nerve: arise from nasociliary nerve, as it crosses the optic nerve, pass forward enter eyeball supply sensory fibres to ciliary body, iris, cornea. It also carry some postganglionic sympathetic fibres to dilator pupillae.

e) Posterior ethmoid nerve: enters posterior ethmoid foramen, supplies ethmoidal & sphenoidal air sinus.

Clinical anatomy: When ophthalmic nerve paralysed, ocular conjunctiva becomes insensitive to touch.

Let me know in the comment section, if you have any doubts or errors in the above article.