Optic nerve

Optic nerve: The nerve that connects the eye to the brain and carries the impulses formed by the retina -- the nerve layer that lines the back of the eye, senses light and creates the impulses -- to the brain which interprets them as images. The optic nerve is the second cranial nerve. The cranial nerves emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column. There are twelve cranial nerves. In terms of its embryonic development, the optic nerve is really a part of the central nervous system (CNS) rather than a peripheral nerve. The word "optic" comes from the Greek "optikos", pertaining to sight.