Optic nerve [Neurosurgery Wiki]

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====== Optic nerve ======
The optic [[nerve]], also known as [[cranial nerve]] II, transmits visual information from the [[retina]] to the brain. Derived from the embryonic [[retinal ganglion cell]], a diverticulum located in the [[diencephalon]], the [[optic nerve]] does not regenerate after transection.

The optic nerve may be divided into 4 segments: intraocular (1 mm in length), intraorbital (25–30 mm), intracanalicular (10 mm), and intracranial (10 mm). 

{{::anteriorclinoidprocess.jpg|}}

AC: [[anterior clinoid process]]; ICA: [[internal carotid artery]]; LT: [[lamina terminalis]]; ON: [[optic nerve]]; OlN; [[olfactory nerve]]; SW: [[sphenoid wing]]; TS: [[tuberculum sellae]]; A1: A1 segment of the [[Anterior Cerebral Artery]]; A2: A2 segment of the [[Anterior Cerebral Artery]]; M1: M1 segment of the [[Middle Cerebral Artery]]


{{ http://www.ganfyd.org/images/8/84/Optic_nerve_projections.png}}

====== Diameter ======


[[Optic nerve diameter]]

===== Pathology =====
see [[Optic nerve injury]].

In cases where the tumour is confined to the [[optic nerve]]s, they can safely be referred to as [[optic nerve glioma]]s. Often optic nerve gliomas are either centred on or extend to involve the chiasm and optic radiations. In such cases, they are difficult to distinguish from [[hypothalamic glioma]]s and such a distinction is in most instances artificial. In such more posterior cases the term hypothalamic-optochiasmatic glioma is perhaps more accurate although it certainly does not roll off the tongue. 

As such, generally, the term [[optic pathway glioma]] is favoured, recognising that there may be involvement of the [[hypothalamus]]
((https://radiopaedia.org/articles/optic-pathway-glioma)).