part_of part of part of extends_fibers_into neuron projection bundle brain visual system neuron projection bundle connecting eye with brain for the vertebrate-specific structure, see UBERON:0000941 (cranial nerve II) TADS:0000232 UBERON:0004904 optic nerve A neuron projection bundle that connects the retina or its analog in the eye with the brain. This includes the vertebrate optic nerve (not truly a nerve) as well as analogous structures such as the Bolwig nerve in Drosophila. EV:0100351 optic nerve (generic) BTO:0000966 photoreceptor array