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Neuroanatomy
Visual System
| Question | Answer |
|---|---|
| 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
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