optic nerve
optic nerve
optic nerve
op′tic nerve′
n.
optic nerve
| Noun | 1. |  optic nerve - the cranial nerve that serves the retina |
| 单词 | optic nerve | |||
| 释义 | optic nerveoptic nerveoptic nerveop′tic nerve′n. optic nerve
optic nerveoptic nerve:see visionvision,physiological sense of sight by which the form, color, size, movements, and distance of objects are perceived. Vision in Humans The human eye functions somewhat like a camera; that is, it receives and focuses light upon a photosensitive receiver, the retina. ..... Click the link for more information. . Optic Nerve(nervus opticus), the second pair of cranial nerves, along which visual stimuli received by the sensory cells of the retina are transmitted to the brain. The optic nerve is not a typical cranial nerve in structure, but is like brain matter transported to the periphery and connected with the nuclei of the diencephalon, and through them also with the cortex of the large hemispheres. The optic nerve originates in the ganglial cells of the retina. Processes of these cells gather into the optic disk (or papilla), which is located 3 mm closer to the middle from the posterior pole of the eye. Farther on, the bundles of nerve fibers penetrate the sclera in the region of the lamina cribrosa and are surrounded by meningeal structures, forming a compact nerve trunk. Located among the bundles of fibers of the optic nerve are the central artery of the retina and the analogous vein. Together with the ophthalmic artery, the optic nerve passes into the cranial cavity through the optic canal, which is formed by a small wing of the sphenoid bone. Within the cranial cavity, the optic nerve goes from each eye toward the posterior and closer to the middle for about 1 cm, and then approaches the optic nerve of the opposite side over the sella turcica of the sphenoid bone; anterior to the hypophysis the optic chiasma is formed, where there is a crossover only of the axons of the cells of the nasal half of the retina. After the chiasma, the optic nerve continues into the optic tracts. V. V. KUPRIIANOV optic nerve[′äp·tik ‚nərv]Optic nerveoptic[op´tik]The rods and cones of the retina are connected with the optic nerve which leaves the eye slightly to the nasal side of the center of the retina. The point at which the optic nerve leaves the eye is called the blind spot because there are no rods and cones in this area. The optic nerve passes through the optic foramen of the skull and into the cranial cavity. It then passes backward and undergoes a division; those nerve fibers leading from the nasal side of the retina cross to the opposite side while those from the temporal side continue to the thalamus uncrossed. After synapsing in the thalamus the neurons convey visual impulses to the occipital lobe of the brain. Degenerative and inflammatory lesions of the optic nerve occur as a result of infections, toxic damage to the nerve, metabolic or nutritional disorders, or trauma. Syphilis is the most frequent cause of infectious disorders of the optic nerve. Methanol (methyl alcohol) is highly toxic to the optic nerve and can cause total blindness. Diabetes mellitus and anemia are examples of metabolic and nutritional disorders that can lead to damage to the optic nerve and produce serious loss of vision. Treatment of optic neuritis is aimed at control of the primary cause of the disorder. Cortisone and similar steroids are often used to relieve symptoms; however, nothing can be done to regain sight lost through damage to the nerve. optic nerveoptic nerve2nd cranial nerve Anatomy A bundle of > 1 million nerve fibers that carries afferent/senosry fibers from the retinal gangliion cells, passing out of the orbit via the optic foramen (canal) to the optic chiasm, where part of the fibers cross to the opposite side, passing though the optic tract to the geniculate bodys, pretectum, and superior colliculus in the brainOptic nerveoptic nerve
Synonyms for optic nerve
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