Definition of Nerve, opticNerve, optic definition - medical term The optic nerve connects the eye to the
brain. The optic nerve carries the impulses formed by the retina. The
retina is the nerve layer that lines the back of the eye that senses
light and creates impulses. These impulses are dispatched through the
optic nerve to the brain, which interprets them as images. Using an
ophthalmoscope, the head of the optic nerve can be easily seen. It
can be viewed as the only visible part of the brain (or extension of
it).
The optic nerve is the second cranial nerve. The cranial nerve
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 a part
of the central nervous system (CNS) rather than a peripheral
nerve.
The word "optic" comes from the Greek "optikos", pertaining to
sight.
Aside from the optic nerve, the eye has a number of other
components. These include the cornea, iris, pupil, lens, retina,
macula, and vitreous.
The cornea is the clear front window of the eye that
transmits and focuses light into the eye.
The iris is the colored part of the eye that helps
regulate the amount of light that enters the eye.
The pupil is the dark aperture in the iris that
determines how much light is let into the eye.
The lens is the transparent structure inside the eye that focuses
light rays onto the retina.
The retina is, as mentioned, the nerve layer that lines the back
of the eye, senses light and creates impulses that go through the
optic nerve to the brain.
The macula is a small area in the retina that contains
special light-sensitive cells and allows us to see fine details
clearly.
The vitreous humor is a clear, jelly-like substance that
fills the middle of the eye.
In sum, the optic nerve is uniquely a part of both the eye and the
brain. It is embryologically the brain's envoy to the eye and
functionally the eye's envoy to the brain.
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