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Whats responsible for waking you up?
Reticular activating system
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Reticular activating system relays where?
Is it specific?
- Relays to the cortex
- It is not specific
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What is responsible for unconscious proprioception?
Cerebellum
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What is responsible for conscious proprioception?
C. Cortex
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Interoreceptors relay where?
Brainstem
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Noci ceptors sense what kind of stimuli?
Pain
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How do nociceptors sense pain?
free nerve endings sense extracellular K+ which is normally low but upon injury is released from ICF to ECF
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What type of somatosensory relay is found above T6?
- Fasciculus Cuneatus
- Fasciculus Gracilis
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What type of somatosensory relay system is found up to T6?
Fasciculus gracilis
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What kind of somatosensory relay is found in the dorsal column?
Epicritic Relay
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What makes up the internal Arcuate Fibers?
Axons of gracile and cuneate nuclei
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The internal arcuate fibers turn into what as they ascend?
Medial Leminiscal Relay
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The Epicritic relay fibers desiccate where?
At medulla level
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Epicritic stimuli are what?
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What are protopathic stimuli?
- diffuse touch
- temp- cold and hot
- pain--slow and fast
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Medial leminiscal relay synapses onto what nuclei?
Nucleus ventralis lateralis of thalamus (VPL)
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VPL synapses onto what?
somatosensory area 3--1--2
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In the spino cerebellar relay, Ia fibers carry what type of stimuli?
Unconscious proprioception
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Ia fibers use what ? to reach external cuneate nuclei?
Fasciculus Cuneatus
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What mediates unconscious proprioception?
cerebellum
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Nt for C fiber(slow pain)
substance P
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Anterolateral/spinal leminiscus relay is what type of relay?
Protopathic
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What type of tract descends 2-3 segments?
Protopathic
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Which relay has nucleus proprius?
Protopathic relay
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Which relay crosses over on the anterior white commissure?
- Protopathic
- note...flexor crossed extensor also crosses it
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Which relay has spino thalamic and spinoreticular formations?
Protopathic
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Where do epicritic cross over?
Protopathics?
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Band of bilateral protopathic loss occurs in relation to the lesion?
at the lesion
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Slow pain uses what fibers?
C fibers
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Are C fibers myelinated, non myelinated, unmyelinated?
unmyelinated
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What neurotrasmitter is used for slow pain?
substance P
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Substantia gelatinosa is an interneuron found in what pathway?
Slow Pain
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Slow pain fibers (via reticular formation) synapseonto what in the thalamus?
- Cingulate gyrus
- prefrontal cortex
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The jaw Drop reflex of CN V is called what?
Jaw-drop reflex
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Medial leminiscus contains what kind of sensory fibers?
Epicritics
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Spinal leminiscus contains what kind of fibers?
Protopathics
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A lateral medullary lesion would produce what type of sensory loss?
- Ipsilateral protopathic to face
- Contralateral protopathic to the face
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What is phototopic vision?
- color vision
- requires high light
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What is scototopic vision?
- black and white vision
- low lite
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What on the retina provides for high acuity vision?
Fovea (Macula)
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What physiological change do photoreceptors undergo in response to light?
They hyperpolarize
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What is special about the jaw drop reflex?
it comes in to CN V and Leaves from it
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By what mechanism do photoreceptors hyperpolarize?
- phosphodiesterase degrades cGMP
- Sodium permeability decreases
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What parasympathetic nucleus mediates meiosis of the pupil?
Edinger-Westhall Nucleus
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A lesion where would produce dilated pupils?
Mesencephalon (MidBrain)
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Light from what nucleus goes to Edinger-Westhall Nucleus?
Pretectum
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What is the pupillary light deficit?
- Marcus Gunn Pupil...
- pupils do not constrict bilaterally when light is shone into one pupil
- But they both constrict when light is shone into the other pupil
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What would happen in a pupillary afferent deficit?
One pupil constrict but the other doesnt
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What are the 3 events that occur during accomodation?
- 1. Pupils contract
- 2. Eyes adduct
- 3. Lens go from flat to spherical
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In Agryll-Robertson pupil what is lesioned?
- pretectum
- pupil accomodates but does not react
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The bony labirynth contains what fluid similar in composition to what other physiological fluid?
ECF--high Na, low K
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Membraneous Labirynth contains fluid similar in composition to what other physiological fluid?
ICF--high K and Low Na
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Why are sounds perceived to be louder in Bell Palsy?
CN VII is affected which controls stapedius which in turn controls stapes
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Scala media contains what type of lymph?
endolymph high in K and low in Na
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The basilar membrane is thickest where?
Apex
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The basilar membrane is thinnest where?
Base
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The basilar membrane near the apex or the base is best suited to hear high frequency sounds?
Base
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The basilar membrane near apex or base is best suited to hear low frequency sounds?
Apex
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Hair cells are found in?
Organ of corti
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Hair cell, supporting cells and tectorial membrane are found where?
Organ of Corti
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Organ of corti sits on top of what?
Basilar Membrane
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How many are there of inner hair cells in the organ of cort?
1
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How many of outer hair cells are there in the organ of corti?
3-5
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How does the Superior Olivary Nucleus allow for localization of sound?
Because the ventral nucleus from the side from which sound is heard first synapses onto that side's Superior Olivary nucleus and then onto the contralateral superior olivary nucleus
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What is the purpose for bilateral input onto the superior olivary nucleus?
for localization of sound
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The dorsal cochlear n. fibers cross over where?
below the 4th ventricle in the middle medulla
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Is the relay for dorsal cochlear n ipsilateral or contralateral?
contralateral
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Superior Brachium is found where?
its a branch of the optic tract
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Inferior Brachium is found where?
part of the auditory path
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Up to what point can hearing loss be ipsilateral?
Up to the cochlear nucleus
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Why can Ipsilateral hearing loos be only caused in a region up to the cochlear nucleus?
Because after the cochlear nucleus it is bilateral
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What puts tension on the tectorial membrane?
Outer hair cells via corticofugal control
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The reticular activating system wakes up the cortex by synapsing onto what nuclei?
Inferior Colliculus
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Where is the vision association center located in the brain?
Parieto temporal lobe
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Superior brachium and superior colliculus are found in where?
Vision
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Inferior brachium and inferior colliculus are found where?
hearing
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Superior brachium and Superior colliculus project onto the parietal temporal association center via what nucleus?
Palvinar nucleus of thalamus
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Medial geniculate nucleus is found where?
Hearing
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Lateral geniculate nucleus is found where?
Vision
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Lesion of the cervical cord that produces horners syndrome affects which structure?
Descending hypothalamic tract
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Lesion of the thoracic cord that produces horners syndrome affects what structure?
Antero-medial column
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What does enkaphalin do?
- block C fiber presynaptically
- via 5 HT
- no substance P released
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Why arent epicritics lost in a lateral medullary lesion?
- because they run more medially so only ipsi protos to face are lost
- contra protos to the body
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Lehrmet's sign is characteristic for what?
cervical cord sign
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CVA to area 8 on the left would produce what ?
eyes deviate ipsilaterally to the left
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Saccadic eye movements use what area?
area 8
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Smooth pursuit uses what area?
17,18,19
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What is the difference between vestibulo oculomotor reflex and Optokinetic Reflex?
- vestibulo oculomotor--in @ 8
- out on 3 and 6
- Optokinetic is in on 2
- out on 3 and 6
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What nucleus is responsible for localization of sound?
Superior olivary nucleus
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What is the differential between an Acoustic Shwanoma and Menier's disease/
- Menier's---CN VIII only
- Shwannoma--CN VIII, V and VII
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Basket and stellate cells are inhibitory or excitatory?
inhibitory
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Climbing fibers are for new motor behavior or learned motor behavior?
new motor behavior
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What is the only excitatory cell in the cerebellum?
Granular cell
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