Before revision: Structure The optic nerve has been classified as the second of twelve paired cranial nerves, but it 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.
After revision: Structure The optic nerve has been classified as the second of twelve paired cranial nerves, but it is technically a myelinated tracta classical nerve of 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.