Norden - Visual Flashcards
The four main central targets for retinal cell ganglia axons are ?
Lateral geniculate nucleus
Superior colliculus
Pretectum
Hypothalamus
Why do retinal ganglion cells synapse in the hippocampus?
Circadian rythms
Each LGN processes information from where?
The contralateral visual hemifield of vision
The lateral geniculate gets its blood from ?
Anterior choroidal (Internal carotid)
Posterior cerebral A. (Basilar artery)
The geniculo calcarine tract (aka optic radiations) project where?
They go from LGN to area 17
Axons coming out of the medial part of the LGN go to what part of the calcarine cortex?
Cuneus gyrus
Axons coming out of the lateral portion of the LGN travel in Meyer’s Loop to where?
Lingual gyrus of the calcarine cortex
The optic radiations represent the _____ ____ of vision
Contralateral hemifield
Other higher-order visual cortical areas in occipital, temporal and parietal lobes
Extrastriate visual field
Identifying “what” an object is requires projects to extrastriate visual areas of ____
Occipital and temporal lobe
Identifying “ where “ an object is involves projections to extrastriate areas in the ++___+__I_)*(
Occipital and parietal lobes
The superior colliculus sends visual information where?
Thalamus Pons (to send to cerebellum) Cervical spinal cord (to turn head) CN III, IV, VI Reticular formation (for arousal Cortex
Plays a role in orienting to moving stimuli and in directing gaze
Superior colliculus
Describe the pathway in which the superior colliculus sends axons to the cortex?
The superior colliculus projects to the thalamus, a subdivision of the pulvinar to be specific, which then projects to extrastriate visual cortex
RGC’s projecting to the pretectum is part of the pathway that mediates the ______
Pupillary light reflex
What type of RGC’s project to the hypothalamus
RGC’s that are specific for ambient light. They do not otherwise have an effect in vision.
Where in the hypothalamus do ambient light -sensing RGC’s specifically project?
Suprachiasmatic nucleus
The inability to match a face with an identity (occurs due to higher order visual area damage bilaterally)
Prosopagnosia
How can you check an eye?
Look at visual reflexes, eye movements, fundus, changes in vision
The only place in the body where blood vessels and CNS tissue can be observed directly
The fundus
The fovea is ___ mm lateral to the optic disk
3.5
The optic disc is ____ in diameter
1.5mm
Papilledema indicates what?
Increased intracranial pressure
What does increased cranial pressure do in papilledema
Increased cranial pressure causes the subarachnoid space to impinge on the retinal veins, causing nerve head to be congested.
Also impinges on the axo-plasmic transport of RGC axons in the optic nerve
Optic neuritis is a common presenting sign in ?
Multiple sclerosis
Relative afferent pupillary defect
Marcus Gunn pupil
Can be caused by optic nerve inflammation.
Stimulation of the affected eye has a more sluggish direct response relative to the direct response of the unaffected eye.
Marcus Gunn Pupil
Relative afferent pupillary defect (RAPD_
Signs of Shaken baby syndrome
Ecchymosis on the sternum
Retinal hemorrhage
Papilledema
Retinal detachment
Decreased responsiveness
Long term consequences if infants survive shaken baby syndrome
Diffuse axonal injury
Blindness
Epilepsy’
Intellectual impairment
A separation of the brain at the junction of the pons and medulla
Brainstem avulsion.
Loss of an entire 1/2 field of vision
Homonymous hemianopsias
Lesions central (caudal) to the optic chiasms cause?
Homonymous hemianopsias
Nasal retinal fibers project
Contralaterally after the chiasm
Superior retinal quadrants (inferior visual fields) project to the _____ part of the lateral geniculate nucleus
Medial
The inferior retinal quadrants (the superior visual quadrants) projects to the ____ part of the lateral geniculate nucleus
Lateral
The lower retinal fields project :
To the lateral portion of the LGN and then to the lingual gyrus
What part of the calcarine cortex does the macula project to ?
The posterior 1/3
What part of the LGN does the macular retina project to ?
Central
In visual field loss from unilateral lesions posterior to the chiasm, defects are homonymous and respect ?
The vertical meridian
The LGN is located where?
Lateral and posterior in the thalamus
In the thalamus, the _____- is dorsal to both the LGN and the MGN
Pulvinar
The LGN is supplied by the?
Anterior choroidal artery
Branches of posterior cerebral A.
Where do the two divisions of the geniculo-calcarine pathway (optic radiations) reconnect?
In the internal capsule
The subdivisions of the of geniculo-calcarine tract are supplied by?
Branches of the MCA and PCA
Located dorsally in the thalamus
Relays visual information to the extrastriate visual cortex
Receives its major visual input from the superior colliculus
Pulvinar
