Monday, June 27, 2011

Nasociliary Nerve

The nasociliary nerve branches off the ophthalmic nerve, which in turn originates from trigeminal. It is a sensory nerve that divides into the long ciliary, posterior ethmoidal, anterior ethmoidal, and infratrochlear nerves, and a communicating branch to the ciliary ganglion, supplying the mucous membrane of the nasal cavity, the sphenoidal sinus, ethmoidal sinus, dilator pupillea, and cornea. The nasociliary nerve goes into the orbit between the two heads of the lateral rectus muscles and between the superior and inferior rami of the oculomotor nerve (CN III), passing across the optic nerve (CN II) and running obliquely beneath the superior rectus muscle and superior oblique muscle to the medial wall of the orbital cavity. Then it travels through the anterior ethmoidal opening as the anterior ethmoidal nerve and enters the cranial cavity just above the cribriform plate of the ethmoid bone.