ABSTRACT
Innervation of the eye The optic nerve (2nd cranial) enters the orbit from the middle cranial fossa via the optic canal. Its length in the orbit is 3cm, and sheaths of pia mater, arachnoid mater and dura mater surround it. It curves laterally and downwards as it passes forward within the muscle core of the eye, and pierces the sclera medial to the posterior pole of the globe, where the meninges merge with the sclera. The optic nerve receives the central retinal artery during its course. The nasociliary nerve, ophthalmic artery and superior ophthalmic vein lie on top of, and parallel to, the nerve. The short ciliary nerves and vessels surround the anterior portion of the nerve.
