Anatomy
A optic nerve is the 2nd of dozen opposite cranial nerves but is considered to become a share of the central nervous system as it is from either an outpouching of the diencephalon during embryonic development. Consequently, a fibers come covered sustaining myeline by oligodendrocytes rather than a Schwann cells of the peripheral nervous system. This is an crucial issue, when pulp tracks of the mammalian central nervous models (when opposed to the peripheral nervous patterns) come incapable of regeneration & hence optic nerve damage produces irreversible cecity. A fibers from either a retina run along a optic nerve to nine primary ocular nuclei in the brain, from either whence the major relay inputs into the primary visual cortex.

A optic nerve is composed of retinal ganglion cell axons and trend lines cells. It leaves a orbit (eye) via the optic canal, running postero-medially towards a optic chiasm where there is a partial chiasm (crossing) of fibers from either a temporal visual fields of both eyes. Virtually all of the axons of the optic nerve terminate in the lateral geniculate nucleus from where trading tools is relayed to the visual cortex. Its across increases from either astir Unity.Sextuplet millimetre inside a eye, to Tierce.Fin millimetre in the orbit to Quartet.Little phoebe millimeter inside a cranial space. A optic nerve component lengths come 1mm in a world, 25mm in the orbit, 9mm in the optic canal & 16mm in the cranial space prior to joining the optic chiasm. There, unfair chiasma occurs & all about 53% of a fibers cross to form the optic tracts. Virtually all one fibers terminate in the corpus geniculatum laterale.

From either a corpus geniculatum laterale, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain. Extra specifically, fibers carrying trading tools from either a contralateral superior field of regard traverse Meyer's loop to terminate in the lingual gyrus below the calcarine fissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual field terminate more superiorly.

Physiology
A optic nerve contains Ace.Two million nerve fibre. This total is great in comparison a about 130 million receptors in the retina, & implies that real pre-processing takes place in a retina before the signals come sent to the brain through the optic nerve.

A blind spot of a eye is produced by a absence of retina in which a optic nerve leaves the eye. This is because no photoreceptors in this locality.

Role in disease
Damage to the optic nerve often stimulates lasting & possibly severe loss of vision, as well as an abnormal pupillary reflex, which is diagnostically important. A nature and severity of visual field loss will depend in which portions of the optic nerve were damaged. Usually speaking: Damage prior to a optic chiasm affect vision in the field of vision of the equivalent side exclusively. Damage in the chiasma induces loss of vision laterally around two field of regard (bitemporal hemianopsia). It might occur around prominent pituitary adenomata. Damage fallowing a decussatiin is a causal agent of loss of vision on 1 side however poignant each field of regard: the field of vision affected is placed on the paired side of the lesion.

Injury to a optic nerve may be the effect of innate or even heritable problems rather Leber's Hereditary Optic Neuropathy, glaucoma, trauma, toxicity, inflammation, ischemia, infection (very rarely), or compression from tumors or aneurysms. By far, a leash usual injuries to the optic nerve come from either glaucoma, optic neuritis (especially around victims immature than L years aged) & prior ischaemic optic neuropathy (unremarkably around victims older than L). Glaucoma is a group of diseases involving loss of retinal ganglion cells causing optic neuropathy in a pattern of peripheral vision loss, initially sparing central vision.

Optic neuritis is inflammation of the optic nerve. These are associated by using the total of diseases, virtually all notably multiple sclerosis.

Anterior Ischemic Optic Neuropathy is a particular type of infarction that infects patients using an anatomical predisposition & cardiovascular chance factors.

Ophthalmologists, particularly those subspecialists world health organization come neuro-ophthalmologists, are typically better suited to diagnose & handle diseases of the optic nerve.