презентация Opticus

1. TheThe optic nerveoptic nerve, also called, also called cranialcranial
nerve IInerve II, is the, is the nervenerve that transmitsthat transmits
visual information from thevisual information from the retinaretina to theto the
brainbrain..

2. AnatomyAnatomy
The optic nerve is the second of twelve pairedThe optic nerve is the second of twelve paired cranial nervescranial nerves but is considered to be part of thebut is considered to be part of the
central nervous systemcentral nervous system as it is derived from an outpouching of theas it is derived from an outpouching of the diencephalondiencephalon duringduring
embryonic development. The fibers from theembryonic development. The fibers from the retinaretina run along the optic nerve to nine primaryrun along the optic nerve to nine primary
visual nuclei in the brain, from whence a major relay inputs into thevisual nuclei in the brain, from whence a major relay inputs into the primary visual cortexprimary visual cortex..
The optic nerve is composed ofThe optic nerve is composed of retinalretinal ganglion cellganglion cell axons and support cells. It leaves theaxons and support cells. It leaves the orbitorbit (eye)(eye)
via thevia the optic canaloptic canal, running postero-medially towards the, running postero-medially towards the optic chiasmoptic chiasm where there is a partialwhere there is a partial
decussation (crossing) of fibers from thedecussation (crossing) of fibers from the temporaltemporal visual fields of both eyes. Most of thevisual fields of both eyes. Most of the axonsaxons ofof
the optic nerve terminate in thethe optic nerve terminate in the laterallateral geniculategeniculate nucleusnucleus from where information is relayed tofrom where information is relayed to
the visual cortex. The optic nerve component lengths are 1 mm in the globe, 25 mm in the orbit, 9the visual cortex. The optic nerve component lengths are 1 mm in the globe, 25 mm in the orbit, 9
mm in the optic canal and 16 mm in the cranial space before joining the optic chiasm. There,mm in the optic canal and 16 mm in the cranial space before joining the optic chiasm. There,
partial decussation occurs and about 53% of the fibers cross to form the optic tracts. Most ofpartial decussation occurs and about 53% of the fibers cross to form the optic tracts. Most of
these fibers terminate in the lateral geniculate body.these fibers terminate in the lateral geniculate body.
From the lateral geniculate body, fibers of theFrom the lateral geniculate body, fibers of the optic radiationoptic radiation pass to thepass to the visual cortexvisual cortex in thein the
occipital lobeoccipital lobe of the brain. More specifically, fibers carrying information from the contralateralof the brain. More specifically, fibers carrying information from the contralateral
superior visual field traverse Meyer's loop to terminate in the lingual gyrus below the calcarinesuperior visual field 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 visualfissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual
field terminate more superiorly.It also gives us the power to see.field terminate more superiorly.It also gives us the power to see.

3. PhysiologyPhysiology
The optic nerve contains 1.2 million nerve fibers.The optic nerve contains 1.2 million nerve fibers.
This number is low compared to the roughly 100This number is low compared to the roughly 100
million photoreceptors in the retina,million photoreceptors in the retina,[1][1]
and impliesand implies
that substantial pre-processing takes place inthat substantial pre-processing takes place in
the retina before the signals are sent to the brainthe retina before the signals are sent to the brain
through the optic nervethrough the optic nerve
The eye's blind spot is a result of the absence of retinaThe eye's blind spot is a result of the absence of retina
where the optic nerve leaves the eye. This is becausewhere the optic nerve leaves the eye. This is because
there are no photoreceptors in this area.there are no photoreceptors in this area.

4. Role in diseaseRole in disease
 DamageDamage beforebefore the optic chiasm causes loss ofthe optic chiasm causes loss of
vision in the visual field of the same side only.vision in the visual field of the same side only.
 DamageDamage inin the chiasm causes loss of visionthe chiasm causes loss of vision
laterally in both visual fields (bitemporallaterally in both visual fields (bitemporal
hemianopia). Damagehemianopia). Damage afterafter the chiasm causesthe chiasm causes
loss of vision on one side but affecting bothloss of vision on one side but affecting both
visual fields: the visual field affected is locatedvisual fields: the visual field affected is located
on the opposite side of the lesion.on the opposite side of the lesion.