the optic nerves from the eyes join at​ the
Optic nerve
The optic nerve leaves the orbit ( eye socket ) via the optic canal , running postero - medially towards the optic chiasm , where there is a partial decussation ( crossing ) of fibres from the temporal visual fields ( the nasal hemi - retina ) of both eyes . The proportion of decussating fibers varies between species , and is correlated with the degree of binocular vision enjoyed by a species . Most of the axons of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex , while other axons terminate in the pretectal nucleus and are involved in reflexive eye movements . Other axons terminate in the suprachiasmatic nucleus and are involved in regulating the sleep - wake cycle . Its diameter increases from about 1.6 mm within the eye to 3.5 mm in the orbit to 4.5 mm within the cranial space . The optic nerve component lengths are 1 mm in the globe , 24 mm in the orbit , 9 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 of these fibres terminate in the lateral geniculate body . 
The optic nerve leaves the orbit ( eye socket ) via the optic canal , running postero - medially towards the optic chiasm , where there is a partial decussation ( crossing ) of fibres from the temporal visual fields ( the nasal hemi - retina ) of both eyes . The proportion of decussating fibers varies between species , and is correlated with the degree of binocular vision enjoyed by a species . Most of the axons of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex , while other axons terminate in the pretectal nucleus and are involved in reflexive eye movements . Other axons terminate in the suprachiasmatic nucleus and are involved in regulating the sleep - wake cycle . Its diameter increases from about 1.6 mm within the eye to 3.5 mm in the orbit to 4.5 mm within the cranial space . The optic nerve component lengths are 1 mm in the globe , 24 mm in the orbit , 9 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 of these fibres terminate in the lateral geniculate body .
The optic nerve leaves the orbit ( eye socket ) via the optic canal and joins the optic chiasm .
The optic nerve leaves the orbit ( eye socket ) via the optic canal , running postero - medially towards the optic chiasm , where there is a partial decussation ( crossing ) of fibres from the temporal visual fields ( the nasal hemi - retina ) of both eyes . The optic nerve component lengths are 1 mm in the globe , 24 mm in the orbit , 9 mm in the optic canal , and 16 mm in the cranial space before joining the optic chiasm .