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90 Cards in this Set
- Front
- Back
what is the difference between the retinal field and the visual field?
how does retinal field project onto visual cortex? |
v= left or right view from each eye
r= view on retina of opposite visual field retinal field project to the corrosponding side of the visual cortex (RRF to RVC, LRF to LVC) |
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how are nasal/temporal visual fields projected onto retina and the visual cortex?
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Nasal: to lateral retinal field and ipsilateral cortex to eye ball
Temporal: to medial retinal field and contralateral cortex to eyeball |
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how are superior and inferior quandrants projected on retina and vis. cortex?
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superior VF projects below calcarine fissure in occipital lobe
inferior projects above it |
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describe the neuronal pathway of visual information
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optic fibers, retinal ganglion cells, exit eyeball, optic disk. enter cranial cavity, optic chiasm (lateral geniculate body or superior colliculus), thalamus (optic radiation fibers), visual cortex
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What is a homonymous visual deficit versus a heteronymous visual deficit? Where is the breakdown neuronally?
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homo: same VF of both eyes (rt or left). optic tract, geniculatebody, or geniculocalcarine fissure lesion
hetero: rt FV for one, left for other. Optic chasm lesion |
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VF defecits for lesion on optic nerve
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blindness to same eye (or to one VF, if lesion only affects part of nerve)
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VF defecits for lesion on optic tract
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homonymous hemianopsia
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VF defecits for lesion on optic chasm
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both fibers from nasal retinas: Biltemporal heteronymous hemianopsia (blind in temporal VFs)
one fiber: isilateral temporal part of retnina, nasal hemianopsia in one eye |
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VF defecits for lesion on optic radiation fibers
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outer geniculocalcarine: left upper quadtranopsia
dorsal geniculocalcarine: right upper quadtranopsia |
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VF defecits for lesion on the occipital lobe
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visual agnosia (doens't recognize visual stimuli)
prosopoagnosia (doen'st recognize faces) |
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What specific thalamic nuclei serve as major gateways for transmission of auditory and visual information? Where do these nuclei project in the cortex?
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aud: medial geniculat ebody (to heschls gyrus)
vis: lateral geniculate body (to occipital lobe) |
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where is the inferior colliculus and what is it's function?
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-auditory and visual reflexes coordinated here
-lateral lemniscus fibers ascend via pons to here -located in the midbrain |
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where is the superior colliculus and what is it's function?
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-in midbrain, rostral to inferior colliculus
-mediates visual reflexes |
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where is the pineal gland and what is it's function?
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-located rostro-dorsal to superior colliculus
-produces melatonin |
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where is the cerebral aqueduct and what is it's function?
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-in lower caudal midbrain
-contains cerebrospinal fluid, and connects the third ventricle in to the fourth ventricle |
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where is the medial geniculate nucleus and what does it do?
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-thalamic relay center for auditory stiumli
-recieves info from ipsilateral inferior colliculus -projects ventrally and caudally into internal capsule -terminate in ipsi heschls gyrus |
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where is the lateral geniculate nucleus and what does it do?
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-receives info from retina, major visual processor
-part of the thalamus |
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where is the fourth ventricle and what does it do?
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-between pons and cerebellum
-provides CSF to midbrain and cerebellum |
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describe the path of the corticospinal tract
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precentral gyrus, corona radiata, posterior limb of internal capsule, cerebral peduncle, BS, becomes lateral corticospinal tract, ends in SC
-90% of fibers decusate at medulla (lateral CST) -10% (anterior CST) don't |
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what systems compromise the pyramidal tracts?
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corticospinal and cotico bulbar
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describe the path of the coricobulbar tract
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-lower precentral gyrus, internal capsule (genu), pes pedunculi, cranial nerve nuclei, pontine nuclei (to contralateral side)
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Describe the Indirect Activation Pathway (IDAP) and tracts that make up this efferent system
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aka extrapyramidal tract
-maintains posture, muscle tone, etc -comprised of vestibulospinal, reticulospinal, rubrospinal, and tectospinal tracts -inhibits extensor muscle contraction, facilitates flexor activation |
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What is the Final Common Pathway (FCP)? What structures make up the FCP and where is it located, roughly?
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-at the SC level
-dorsal roots (sensory) and ventral roots (alpha/gamma motor) merge to yield spinla nerves |
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what do alpha and gamma motor neurons innervate, and where are they?
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alpha: extrafusal muscle fibers. bone to tendon. afferent impulses. muscle contractions
Gamma: control both ends of intrafusal muscle fibers. contraction of ends= passive stretch. |
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regarding the face, what will an upper motor neuron lesion result in?
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-affect contralateral LMN inervation to LOWER face and tongue (cranial VII and XII)
-lesion above caudal medulla decussatoin -central facial weakness |
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regarding the face, what will an lower motor neuron lesion result in?
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-lesion below caudal medulla decussaion
-unilateral weakness -"peripheral weakness" |
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describe spastic hemiplegia
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-acute insult (UMN lesion)
-weakness, loss of delicate skills, hypotonia -loss of abdominal reflexes - +babinski |
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describe Bell's palsy
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-LMN lesion, cranial VII
-weakness of entire face on one side -symptoms ipsi to lesion |
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describe pseudobulbar palsy (aka supranuclear palsy)
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due to bilateral UMN lesions of coritcobulbar tracts
-some spasticity, movement problems -poor smile on command -exaggerated smile with emotional stim |
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describe an alternating hemiplegia
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weakness on the contralateral side of lesion above lesion and ipsilateral weakness below lesion due to lesion at point of decussaion
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describe decerebrate posture
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abnormal body posture
-rigidity, removes arm flexors with increased arm/leg extension -toes point down -head arch back -caused by severe injury at BS below red nucleus but above vestibular nucleus |
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describe decorticate posture
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-rigid
-increased arm flexors, clenched fists, increased leg extensors -arms bend in toward body with wrists and fingers bent & against chest -severe brain damage involving corticospinal tract above red nucleus in midbrain region |
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describe LMN vs UMN innervation to the face
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LMN: ipsilateral, unilateral
UMN: BIlateral, affects both sides of upper or lower face |
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describe symptoms of an UMN lesion to the DAP
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-loss of skilled volluntary movement
-hyPOtonia -hyPOrelfexia - +babinski -decorticate posturing |
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describe symptoms of an UMN lesion to the IDAP
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-poor control of posture/tone/DAP support
-hyPERtonia -hyPERreflexia -decerebrate posturing |
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what role does the cerebellum play in afferrent and efferent innervation?
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-excites both
-integrates and coodinates execution of smooth, directed movements |
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how do symptoms of a cerebellar lesion present?
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ataxia
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what are the basal ganglia control circuits?
what are their functions? |
-BG, Substantia nigra, subthalamus, cerebral cortex
-plan and program postural and supportive componants of motor activity and initiation of movement |
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what muscles move the eye?
what nerves innervate them? |
-superior and inferior rectus, lateral and medial rectus, superior and inferior oblique muscles
-cranials III, IV and VI |
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which hemisphere innervates each muscle of the eye?
what will a left hemisphere lesion of these nerves look like? |
cranial III--same side
cranial VI--opposite side L lesion--eye looks left (cannot look right |
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sypmtoms of an UMN lesion
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-spastic paralysis
-increased muscle tone (hypertonia) - +babinski -hypereflexia |
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symptoms of a LMN lesion
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-weakness (flaccid)
-decreased muscle tone (hypotonia) - -babinski -hyporeflexia -signs of muscle devernation (fasiculations) |
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what is indicated by the absense of these visual reflexes?
-consensual reflex (pupil constricts to light) -accomodation reflex (lens focus, pupil restricts) |
cr: problem in neuronal pathway from eye to midbrain (lateral geniculate nucleus)
ar: problem in neural network from vis. cortex back to eye (suprior colliculus) |
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What is indicated by these visual problems?
-conjugate gaze (cannot move eyes to contralataral side) -nystagmus (tremor-like eye movements) -coma -doll's eyes |
cg: lesion to visuomotor area (Brodman's 8)
N: BS lesion coma: depressed BS activity de: BS or BG lesions |
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what id Darrow's hypotheses on MOC function?
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1. Extend dynamic range - a gain control system
2. Control masking from background noise 3. Protect the inner ear from acoustic injury |
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what are Darrow's speculated function of LOC?
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1) LOC protects the cochlea from acoustic injury
2) LOC maintains bilateral symmetry of neural excitability |
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what is the basic function and structure of the cochlea?
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f: transmits electrical signals to the brain for sound perception
s: scala vestibuli (perilymph), scala media (endolymph), scala tympani (perilymph) |
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where are high and low frequency sounds perceived in the cochlea and cortex?
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high F: lower cochlea, anterolateral Heschl's gyrus
low F: higher cochlea, posteromedial Heschl's gyrus |
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describe the central auditory pathways including specific ganglia, nuclei, and neuronal projections.
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cochlear nuclear complex, superior olivary complex, lateral lemniscus, inferior colliculus, brachium of inferior colliculus, medial geniculate body (thalamus), geniculocortical fibers (auditory radiations), heschls gyrus
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Where is the Primary auditory cortex?
the auditory association cortex? |
pac: heschl's gyrus
aac: Wenicke's area |
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How is acoustic information perceived on a cortical level?
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-major inputs to PAC are from contralateral ear
-few projections from ipsilateral ear |
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What is meant by bilateral auditory representation, sound source localization, and tonotopic representation with respect to hearing?
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bilat: PAC receives info from BOTH ears
local: sound reaches ipsi sup. olive. nuc. first, then contra tonotop: high Fo percieved in posteromedial heschls, low Fo in anterolateral heschls |
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How can you assess hearing on a central level?
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speech reception threshold
word recognition scores |
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What is electromotility?
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Outer Hair Cells change length in response to elctric stimuli
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What are the four processes of cochlear function?
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-Sound pressure generates Basilar Membrane motion
-Outer Hair Cells amplify motion -Inner Hair Cells transduce motion into electricity -Auditory Nerve transmits electrical activity to the brain |
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How does one test OHC function and IHC auditory nerve function?
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otoacoustic emissions
auditory brainstem response |
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describe IHC transduction
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-Sensory hairs vibrate, "tip-links" open ion channels into IHC
-Ions flow into IHC, changing electrical potential in IHC -Electric potential causes chemical neurotransmitter release from IHC synapse -Neurotransmitter diffuses to nerve fiber and excites electrical activity in the form of action potentials |
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Describe MOC nerve cells and LOC nerve cells
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MOC: innervate outer hair cells, amplify low F sounds. ACh
LOC: innervate inner hair cells. ACh, GABA, DA, CGRP, Ucn, Opioids. Unmyelinated |
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Describe Type I audtory nerve fibers
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-large
-myelinated -synapse with Inner hair cells -make up 90-95% of auditory fibers |
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What is retrocochlear dysfunction?
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occurs as a result of disorders affecting the auditory nerve; for example, a tumour growing on the vestibular nerve
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describe these 3 errors of refraction:
-hypermetropia -myopia -astigmatism |
H; fartightedness
m: nearsightedness as: irregular shape in cornea/lens |
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describe these 3 color vision problems:
-ptotanopic -deuteranopic -tritanopic |
p lacks red cones
d: lacks green cones t: lacks blue cones |
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what is a visual agnosia?
prosopoagnosia? what causes them? |
vis: doesn't recognize visual stimuli
pro: doesn't recognize faces cause: occipital lobe lesions |
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What are some of the functions of thet vestibular system?
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-integrates info from semicircular canals
-regulates position of head and body -monitros writing motor reflexes -coodinates head and body movements -controls eye fixation |
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details of cranial nerve VIII
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-made of vestibular nerve and cochlear nerve
-transmits afferent info to CNS -involved in balance and perception of sound, integrates them |
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what are the 1st, 2nd, and 3rd order neurons of the auditory nerves?
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1: spiral ganglia
2: cochlear nuclei 3: thalamus |
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describe the dorsal acoustic stria
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-cross midline at pontomedullary junction
-terminate in contralateral lateral lemniscus |
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describe the intermediate acoutic stria
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-project both ipsi and contra to the superior olivary complex
-main body terminate in contralateral lateral lemniscus |
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describe the trapezoid body fibers
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-cross midline and terminate in contra. superior olivary nucleus
-largest and most important of 3 cochlear projections -ipsi fibers go to either ipsi SON or ispsi Lat.Lem. |
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describe the superior olivary nucleus
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-recieved bilateral input from both cochlear nuclei
-sensitive to time and intensity differences -plays part in localization |
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describe the Lateral Lemniscus
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-primary ascending auditory pathway
-in midbrain, extends via SON to InfColl -fibers ascent laterally in pontine tegmentum |
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describe the Inferior Colliculus
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-commisural fibers here permit crossing and integration of binaural and monaural aud. info
-aids in localization -auditory and vis. reflexes coordinated at this juncture |
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Describe the Medial Geniculate Body
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-thalamic relay center for auditory stimuli
-recieves info from ipsi inferior colliculus -projects geniculocortical fibers vent. and caud. to IntCap -terminate in ipsi Heschl's |
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symptoms of Vertebro-Basilar vascular insufficiency
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-vertigo (in 2/3 of cases)
-ataxic (incoordination), diplopia (double-vision) -weakness, halucinations -sometimes Visual Field deficits, blindness, headaches, HL, dysarthria, numbness |
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sypmtoms of vertebro-basilar stroke
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-ispi HL
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symptoms of AICA infarct
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-ipsi facial weakness
-ipsi protopathic loss to face -contra protopathic loss to body -ipsi deafness/HL |
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Describe the conceptualization level of the DAP
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-conscious awareness, intentional action
-cog. and affective in nature -establish goal for action -bilateral, widespread cortically |
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describe the spacial-temporal planning (linguistic planning) level of the DAP
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-interaction between symptoms
-coodination between linguistic neural networks with motor acts and temporal sequencing -phoneme selection and ordering |
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describe the conceptual-programming level of motor speech planning/programming (DAP)
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-plan for neuromuscular execution organized
-intimately connected to linguistic planning |
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what is the function of the Indirect Activation Pathway?
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-mediates subconcious automatic muscle activities
-ex, posture and muscle tone |
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tracts of the IDAP
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corticorubral
corticoreticular rubrospinal reticulospinal vestibulospinal |
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What is the function and structures of the Final Common Pathway?
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-to stimulate muscle contraction and movement
-made of cranial nerves and spinal nerves |
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describe the function and structures of the Basal Ganglia Control Circuits
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-plans and programs postural and supportive componants of motor activity
-made of BG, Sub. Nigra, subthalamus, cerebral cortex |
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describe the function and structures of the Cerebellar Control Circuits
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-integrates and coordinates execution of smooth directed movments
-made of cerebellum, cerebellar beduncles, retic. formation, red nucleus, pontine nucleus, inferior olive, and cerebral cortex |
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Which cranial nerves provide bilateral innervation?
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V, Trigeminal (jaw)
VII, Facial (upper face) IX, glossopharyngeal (slallow) X, Vagus (larynx, pharynx, VFs) |
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which nerves have greater UMN contralateral innervation?
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VII, facial (LOWER face)
XII, hypoglossal (tongue) |
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what do Muscle Spindles do?
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-identify degree and rate of change in muscle length
-maintain muscle tone -contain intrafusal fibers -lie parallel to extrafusal (striate) fibers |
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what do golgi tendon organs do?
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-monitor degree of muscle tension/contraction
-reflexively stretch to reduce muscle tension -prevents contraction |
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Symptoms of UMN lesions
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-unilateral weakness to contralateral side if lesion is above pyramidal decussaion
-ipsilateral weakness if below -Chronic: spasticity, gradual weakness -acute: flaccidity or hypotonia, sudden weakness |
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symptoms of LMN disease
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-segmental loss
-musculature is flaccid, ultimately atrophies -deep tendon reflexes are depressed -fasiculations notes with loss of innervation |