All are true about optic nerve except -a) Arises from axons of bipolar neuronsb) 4 cm longc) Covered by 3 layers continuous with meningesd) Crossed by ophthalmic artery

The neurosensory layer of retina contains three mains neurosensory cells: - Photoreceptors, i.e. rods & cones; bipolor cells (in inner nuclear layer); and ganglionic cells (in ganglionic cell layer). Axons of ganglionic cells (multipolar cells) form the optic nerve. Length of optic nerve is 47-50 mm. Like other parts of CNS, the optic nerve is covered by meningeal sheaths (Pia, arachnoid and dura mater) as soon as it leaves the eyeball. Intercanalicular part of optic nerve is crossed by ophthalmic artery.