|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.)|
|Gray's||subject #200 888|
|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.
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. After giving the anterior ethmoidal nerve, it terminates as the infratrochlear nerve on the medial margin of the orbit.
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.
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.
- SUNY Figs 29:03-08 - "A deeper dissection of the right orbit from a superior approach."
- Norman/Georgetown lesson9 (nasalseptumner)
- Norman/Georgetown cranialnerves (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 As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.