<prompt> Which of the following pa of optic nerve is longest?IntraorbitalIntraocularIntracranialIntracanalicular  <response>: Intra-orbital is the longest pa of optic nerve. Cranial Nerve Optic nerve arises from ganglion cell axons. Length 50 mm. 40 mm in few texts Can be considered as pa of brain 2nd order neuron Pas: Intraocular1, Intraorbital2, Intracanalicular3, Intracranial4. Smallest pa of optic nerve is Intraocular Longest pa : Intraorbital. 