Optic nerve
The optic nerve connects the eye to the brain. The optic nerve carries the impulses formed by the retina, the nerve layer that lines the back of the eye and 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.
Read Also:
- Optic nerve head
The circular area in the back of the inside of the eye where the optic nerve connects to the retina.
- Optic nerve pathways
The course of the chemical and electrical impulse from light stimulating the retina as it passes from the optic nerve to the vision center of the brain. The left and right branches of the optic nerves join behind the eyes, just in front of the pituitary gland, to form a cross-shaped structure called the optic […]
- Optic neuroma
A rare benign tumor of the optic nerve.
- Optician
A specialist in fitting eyeglasses and making lenses to correct vision problems. An optometrist performs eye examinations and writes prescriptions for corrective lenses; an optician fills that prescription.
- Optometrist
A practitioner who provides primary eye and vision care, performs eye examinations to detect vision problems, and prescribes corrective lenses to correct those problems. Some optometrists also make and fit eyeglasses, but many leave that job to opticians. An optometrist is a doctor of optometry (OD), not an MD. When an optometrist detects eye disease, […]