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Neuroanatomy

Visual System

QuestionAnswer
Dominant sensory modality, 15,000-20,000 sensory impulses/sec to CNS,____% are visual 80% of sensory impulses are visual
Vision is the most important sense for: Survival/early warning system, Spatio-temporal orientation, Anticipation/feed-forward planning, Visual-manual & visual-motor activities, Communication,Learning, memory, recall
Sight is defined as The actual light passing through the eye
The projection of the image onto the retna is? inverted and reversed
The light patterns turn into neuronal-electirical impulses by the ____. Retna
Vision is defined as Complex process by which the brain organizes and processes information received from eyes and executes learning and memory
What are the three basic layers of the eye called? Outer, middle, inner
Describe the outer layer. Continuation of Dura Mater---Forms the sclera, cornea, and sheath around the optic nerve
Describe the middle layer. Analogous to the arachnoid & pia mater---Highly vascularized, secreation and absorption of aqueous humor--- Forms the pigmented choroid lining, ciliary body, ciliary muscle and the iris
Describe the inner layer. Actually made up of two layers---Forms retina
Where is the aqeous humor located? Aqueous humor is located in the anterior and posterior chambers---Flows and filtered similar to CSF
The Vitreous humor is more “gel-like”, where is it located? Located in the interior of the eye and maintains the shape of the eye
What is the function of the Cornea? Admits light to eye----Refraction
What is the function of the Iris? Regulates amount of light reaching retina----Pupillary constriction/dilation
What is the functioin of the Lens? Inverts and reverses image projected onto retina----30% of focusing (accommodation for near focusing)
What is the function of the Retina? Converts patterns of light into action potentials----Contains the Macula, Fovea, and Optic Disc
The retina is composed of 5 cell types, what are they? Photoreceptors, Bipolar cells, Horizontal cells, Amacrine cells, Ganglion cells
Photoreceptors refer to the ___ and ___? Rods & Cones
The Ganglion cells becom the ____? the optic nerve
The cell types are arranged in ___ layers? 10
Rods & Cones are stimulated by? particles of radiant energy (photons)
What is the function of the Cones? Function in bright light----Specialized for high acuity & color vision
What is the function of the Rods? Function in dim light----Specialized for movement detection & contrast (cannot detect color----Very sensitive
The ___ ___ is where ganglion axons exit eye to form optic nerve, ther are no photoreceptors or other neurons in this area and this creates a blind spot? Optic Disc
The ___ is a circumferential area near lateral edge of optic disk. Macula
The macula is primarily what, specialized for what? Primarily cones; specialized for color vision
The ____ is a depression in center of macula. Fovea
The fovea is exclusively ____, specialized for what? Exclusively cones; specialized for highest acuity
The peripheral retinal areas are made of primarily what, which is specialized for what? Primarily rods; specialized for movement detection, contrast vision
Each eye sees half the right visual field and half of the left visual feild (true/false)? true
Each half of the visual field only has superior or inferior (true/false)? false, there are superior and inferior divisions on each half of the of the visual field.
Name the structures in order of the afferent visual pathway. Eye structures--> Optic nerve--> Optic chiasm--> Optic tract--> Lat. Geniculate neucleus--> Optic Radiations--> Primary Visual Cortex--> Visual Assoc. Areas--> Multimodal Assoc. Areas
In the optic nerve of the pathway, which fibers travel together? The nasal fibers travel with the temporal fibers of the eye on that side.
This is the part of the afferent visual pathway in which the optic nerve decussates and the nasal fibers from each retina cross. Optic chiasm
This is the part of the afferent visual pathway in which each tract contains fibers for the contralateral visual field. Optic tract
This is the thalamic relay nucleus for vision that receives & processes contralateral visual field info from the optic tract. Lateral Geniculate Nucleus
____ ____ are fibers that come from the LGN through the internal capsule (retrolenticular and sublenticular parts) and project to the ___ ___ ___? Optic radiations, primary visual cortex
The outer radiations carry ___ visual quadrant info and inner radiations carry ___ visual quadrant info. superior, inferior
What does the Primary Visual Cortex surround? Calcarine sulcus/ fissure
What Brodmanns' area is the primary visual cortex? 17
The superior part of the sulcus recieves information from the ____ visual field? inferior
The inferior part of the sulcus recieves info from the ___ visual field? superior
The posterior portion of the primary visual cortex recieves information from our _____ vision. Central
The anterior portion of the primary visual cortex recieves information form our ____ vision. Peripheral
After the information is proccessed at the primary visual cortex, it sends the info to the ___ ___ ___. visual association areas
The dorsal stream from the PVC to the visual assoc areas carries what information? location and movement
The ventral stream from the PVC to the visual assoc areas carries what information? color and form
What Broddmanns' areas are the visual assoc areas? 18 and 19
The visual assoc area processes and integrates the information before sending it to the ___ ___ ___ ___ ___. parietal-occipital-temporal assoc. area
The parietal-occipital-temporal assoc. area is involved with ____ & ____ ____concepts. visuospatial and visual perceptual
Defecits are often named for the visual field (affected/non-affected) affected
This defecit is characterized by half of the visual field being nonfunctional, right or left. Hemianopsia
This visual defecit has one-quarter of the visual field nonfunctional, superior or inferior. quadrantanopsia
This visual defecit is characterized by loss of the same field for each eye. homonymous
This visual defecit is characterized by loss of diferent feild loss for each eye. heteronymous
This visual defecit has atrophy of macular region and loss of central vision (visual acuity). macular degeneration
This is a blockage of drainage of aqueous humor, increased introcular pressure --> retinal damage, and gradual loss of vision (peripheral then central). Glaucoma
The partial or complete opacity of crystalline lens that contributes to blurred vision (central and peripheral) is called? Cataracts
This defecit is due to trauma, disease, or prematurity. It is partial to total blindness of affected eye and loss of binocular vision --> impaired depth perception. Retinopathies
If you have a lesion here, there will be blindness in the ipsilateral eye and loss of binocular vision --> impaired depth perception. Optic Nerve
If there was a lesion here there would be bitemporal heteronymous hemianopsia and loss of peripheral vision bilaterally. Optic Chiasm
If there were a lesion here(three places)there would be contralateral homonymous hemianopsia and loss of right or left visual field. Optic tract, LGN, or optic radiations
Referring to damage at the primary visual cortex, damage to the right or left visual cortex would cause? homonymous hemianopsia contralaterally
When referring to damage at the primary visual cortex, damage superior to the calcarine fissure would cause? inferior homonymous quadrantanopia contralaterally
When referring to damage at the primary visual cortex, damage inferior to the calcarine fissure would cause? superior homonymous quadrantanopia contralaterally
Damage to bilateral primary visual areas that causes sever blurring and sometimes swiss cheese visual fields is called? corical blindness (both sides)
Damage to the visual assoc areas would cause? visual perceptual/ visuospatial dysfunction
Assoc area dysfunctions may affect? facial recognition, color recognition, movement detection, eye-hand eye-foot or eye-body coordination, knowing where you are related to surroundings, and figure-ground descrimination.
Created by: txst fall 2008 on 2008-10-31



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