Course of the Optic Nerve

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We had a class on optic nerve today.
Our teacher said that the optic nerve "originates" from the retina, and continues up till the commencement of the optic chiasma, and is, approximately, 4 cm long.
My question is,
Why is it considered to be a cranial nerve when it does not even originate from any of the several nuclei in the brain?
I know that it is related to the Edinger-Westphal nucleus and the facial nerve, but if it is so, why isn't it said to be originating from there?

What I thought was,

Since it is a sensory nerve, it brings the sensations from the eye ball to the brain for their processing, so it muct be studied before backwards. (Just like we study "tributaries" for veins and "branches" for arteries!)
But if it is right, then that'd mean that we don't have any nuclei for any of the sensory nerves!
(This is not true, right?)
 

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Ygggdrasil
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Why is it considered to be a cranial nerve when it does not even originate from any of the several nuclei in the brain?

From Wikipedia:
The optic nerve is the second of twelve paired cranial nerves and is technically part of the central nervous system, rather than the peripheral nervous system because it is derived from an out-pouching of the diencephalon (optic stalks) during embryonic development. As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes, rather than Schwann cells of the peripheral nervous system, and are encased within the meninges. Peripheral neuropathies like Guillain-Barré syndrome do not affect the optic nerve.

In other words, developmentally the optic nerve comes from progenitor cells that are part of the central nervous system and functionally, it resembles neurons from the CNS more than neurons in the PNS.
 
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From Wikipedia:
In other words, developmentally the optic nerve comes from progenitor cells that are part of the central nervous system and functionally, it resembles neurons from the CNS more than neurons in the PNS.

It is worth noting that "Cranial" implies it does not connect through the spinal cord. :-)
 
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