Nasociliary nerve

Nerve: Nasociliary nerve
Nerves of the orbit, and the ciliary ganglion. Side view. (Nasociliary is at center.)
Nerves of septum of nose. Right side. (Nasociliary is rightmost yellow line.)
Latin	nervus nasociliaris
Gray's	subject #200 888
From	Ophthalmic nerve
To	long root of the ciliary ganglion, the long ciliary nerves, the infratrochlear nerve, and the ethmoidal nerves

The nasociliary nerve is a branch of the ophthalmic nerve. It is intermediate in size between the two other main branches of the ophthalmic nerve, the frontal nerve and the lacrimal nerve, and is more deeply placed.

Path

The nasociliary nerve enters the orbit between the two heads of the lateral rectus muscles and between the superior and inferior rami of the oculomotor nerve (CN III). It passes across the optic nerve (CN II) and runs obliquely beneath the superior rectus muscle and superior oblique muscle to the medial wall of the orbital cavity. It passes through the anterior ethmoidal opening as the anterior ethmoidal nerve and enters the cranial cavity just above the cribriform plate of the ethmoid bone. It supplies branches to the mucous membrane of the nasal cavity and finally emerges between the inferior border of the nasal bone and the side nasal cartilages as the external nasal branch.

Tests

Since the long ciliary nerves carry the afferent limb of the corneal blink reflex, one can test the integrity of the nasociliary nerve (and, ultimately, the trigeminal nerve) by examining this reflex in the patient. Normally both eyes should blink when either conjuntiva is irritated. If neither eye blinks, then either the ipsilateral nasociliary nerve is damaged, or the facial nerve (CN VII, which carries the efferent limb of this reflex) is bilaterally damaged. If only the contralateral eye blinks, then the ipsilateral facial nerve is damaged. If only the ipsilateral eye blinks, then the contralateral facial nerve is damaged.

Branches

The nasociliary nerve gives off the following branches:

• posterior ethmoidal nerve
• long ciliary nerves
• infratrochlear nerve
• communicating branch to the ciliary ganglion (long root of the ciliary ganglion)
• anterior ethmoidal nerve

PLICA is a mnemonic often used to remember these branches.

Additional images

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  Base of the skull. Upper surface.

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  Plan of oculomotor nerve.

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  Nerves of the orbit. Seen from above.

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  Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion.

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  The sphenopalatine ganglion and its branches.

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  Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure.

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  Pathways in the Ciliary Ganglion.

External links

• SUNY Figs 29:03-08 - "A deeper dissection of the right orbit from a superior approach."
• lesson9 at The Anatomy Lesson by Wesley Norman (Georgetown University) (nasalseptumner)
• cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (V)
• MedEd at Loyola GrossAnatomy/h_n/cn/cn1/cnb1.htm

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.