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119 Cards in this Set
- Front
- Back
somatosensory info converges in ___ lobes of cortex |
parietal lobe |
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primary somsethic area |
(3,1,2); primary sensations |
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secondary somesthetic area |
(40) bilateral connections - bimanual skills |
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sensory association area |
(5,7) perceptual interpretive fxn |
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sensory info flow in brain |
thalamus to primary somatosensory cortex to secondary somatosensory cortex, primary supplementary motor cortex (frontal lobe), posterior parietal cortex sensory association area |
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primary cortical receiving area |
primary somatosensory cortex SI, includes post central gyrus (BA 312) |
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primary somatosensory cortex (SI) neurons are responsive to |
somatosensory stimuli almost exclusively- proprioception, pain, tactile perception (texture, shape, size), vibration, thermal sensation, edge detection, stereognosis |
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how is primary somatosensory cortex organized |
somatotopically organized- sensory homunculus |
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To appreciate the shape, texture, size, weight,and movement of a given object, the somatosensory cortex must integrate theparallel streams of information carried by the |
medial leminiscal pathway |
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destruction of primary somatosensory cortex |
severe deficits in discriminative touch and proprioception on contralesional side of body; deficits in ability to accurately localize and recognize objects by shape, texture and size, vibrating/moving stimuli; also deficits in fine motor coordination |
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secondary somatosensory area (SII) location |
small area in ventral portion of post-central gyrus (40)
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secondary somatosensory area receives extensive input from |
primary somatosensory area and thalamus |
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function of secondary somatosensory area |
shape and texture discrimination and bilateral secondary somatosensory areas strongly linked which could explain involvement in bilateral activities; processing for graphasthesia |
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BA of somatosensory association area |
5, 7 |
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highest degree of convergence of somatosensory info occurs in |
posterior parietal cortex (receives axons of primary and secondary somatosensory association areas) |
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damage to neurons in somatosensory association area |
affect ability to recognize objects even though objects can be felt (tactile agnosia) perceptual deficits: unilateral neglect (non dominant hemisphere lesions), Pusher's syndrome (poor vertical orientation) |
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Pusher's syndrome |
poor vertical orientation (damage to somatosensory association area) |
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contralateral cortical damage in somatosensory cortex |
accurate for touch but unable to localize |
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lesions in somatosensory cortex |
contralateral anesthesia, paresthesia, impaired sensory fxn |
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contralateral parietal lobe damage |
tactile extinction |
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tactile extinction |
ability to sense touch separately but not able to identify bilateral simultaneous touch |
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ability to sense specific touch but unable to identify graphing letters on hand or recognize objects on manipulation |
parietal lobe damage |
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what is usually retained in somatosensory cortical lesions |
vibration sense |
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loss of ability to sense pain (lesion locations) |
damage to pain receptors, lateral spinothalamic tract, primary sensory cortex |
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damage to medial pain systems |
changes in attention to pain modulation of pain sensations and affective response to pain |
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what would indicate that the DC-ML system from peripheral to somatosensory cortex is intact |
awareness of touch and ability to locate; ability to discriminate 2 simultaneous points of contact |
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parietal lobe damage can result in |
unilateral neglect, impaired vertical orientation, tactile agnosias |
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somatosensory system |
elements of PNS and CNS that subserve sensory modalities of touch, vibration, temp, pain, proprioception; sensory info that comes from skin and MSK system |
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flow of somatosensory system (AP if stimulus is strong enough) |
receptors to afferents to cell body in DRG to posterior horn of SC to ascending tracts to brainstem to thalamus to cortex |
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superficial or cutaneous sensation (exteroceptive) |
info from skin and subcutaneous tissue |
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types of superficial/cutaneous sensation |
touch (coarse, discriminative), temp (relative and delta temp), pain (fast and slow) |
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discriminative touch |
light touch, tactile threshold, superficial vibration/flutter, pressure, skin stretch, form, texture |
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coarse touch |
crudely localized touch, tickle, itch |
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pain |
any noxious sensation, sharp, dull, local, diffuse, burning, stabbing; fast or slow |
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deep sensations |
pain and proprioception; info from MSK system |
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types of deep sensations |
joint position sense, kinesthesia, vibration |
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proprioception |
awareness of position and mvm to limbs in relation to each other and the body; knowledge about position of our bodies in space |
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cortical fine touch sensations |
higher order sensations dependent on intact cutaneous and deep sensory fxn |
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cortical final touch sensations types |
2 point discrimination, bilateral simultaneous stimulation, graphesthesia, localization of touch |
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2 point discrimination |
ability to discern that 2 nearby objects touching skin are truly 2 distinct points, not one |
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bilateral simultaneous stimulation |
ability to determine 2 simultaneous stimulations are being applied to opposite sides of body, prox and distal on same side |
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tactile extinction |
from unilateral cerebral damage; inability to recognize 2 simultaneous stimuli on opposite sides of body, or proximally and distally, though either one can be sensed alone |
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graphesthesia |
ability to recognize writing on skin purely by sensation of touch |
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stereognosis |
ability to recognize form of objects by touch |
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barognosis |
ability to tell relative weights |
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combined cortical sensations |
use info from touch and proprioception; stereognosis and barognosis |
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receptor specificity |
receptors respond to 1 type of energy and 1 type of stimulus |
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receptive field |
of sensory neuron is region of space in which presence of stimulus will alter firing of that neuron |
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t/f: distal receptors tend to smaller than proximal + greater density of receptors |
true |
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tonic receptors |
respond as long as stimulus is applied- sustained |
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phasic receptors |
adapt to constant stimulus and stop responding- brief |
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mechanoreceptors |
respond to mechanical deformation of receptor by touch, pressure, stretch, or vibration; mediate sense of touch, proprioceptive sensations |
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chemoreceptors |
involved in senses of pain, itch, and respond to chemicals released by cells including damaged cells post-injury ... pain |
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thermoreceptors |
in skin sense body temp and also changes in temp, temp of ambient air, objects that we touch |
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nociceptors |
subset of each type of 3 receptors types that are specifically responsive to stimuli that threaten or damage tissue- noxious |
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receptors of touch |
mechanoreceptors |
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_____ receptors to skin deformation |
superficial dermis receptors |
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merkel's discs |
pressure, fine touch |
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meissner's corpuscles |
respond to skin deformation and are sensitive to light touch and vibration |
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hair follicle receptors |
respond to hair displacement |
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types of superficial dermis receptors |
merkel's discs, meissner corpuscles, hair follicle receptors |
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deep dermis/subcutaneous fine touch receptors |
info about larger surface areas |
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types of deep dermis/subcutaneous fine touch receptors |
ruffini endings, pacinian corpuscles |
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ruffini endings |
detect skin stretch; contribution to proprioception |
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pacinian corpuscles |
info regarding touch and vibration; contribution to proprioception |
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course touch is mediated via ___ throughout skin |
free nerve endings |
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thermoreception |
ability to sense relative temp and temp changes but not absolute temp |
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adapt to maintained temp (types of nerves) |
free nerve endings |
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specific nociceptors |
free nerve endings which respond to one type of noxious stimulus; respond to high intensity noxious mechanical, thermal, and chemical stimuli; localized pain sensations which are transmitted rapidly via myelinated A-delta fibers- fast sharp pain |
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polymodal nociceptors |
not specific and respond to any high-intensity mechanical stimuli, chemical stimuli, and thermal stimuli; slow transmission of poorly localized pain occurs via unmyelinated C fibers and pain sensation replaced w/ long lasting burning pain |
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receptors involved in proprioception |
muscle spindles, GTOs, joint receptors |
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muscle spindles |
sensory organs of muscles; mechanorecptors buried in skeletal muscle = intrafusal fibers + sensory endings + motor endings |
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respond to lengthening of muscle; muscle activation, rate of change in muscle length |
muscle spindles |
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muscle spindle has what components |
2 types muscle fibers: extrafusal and intrafusal 2 types sensory afferents: Ia, IIb 2 types motor efferent fibers: alpha (stimulate extrafusal fibers) and gamma (stimulate intrafusal fibers) |
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intrafusal fibers |
fusiform, inside fleshy part of skeletal muscle; contractile only at ends; arrangement of nuclei defines 2 types of fibers: nuclear bag and nuclear chain |
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annulospiral sensory endings |
endings of type Ia afferent neurons wrap around central region of each intrafusal fiber
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flower spray sensory endings |
endings of type II afferent neurons end on nuclear chain fibers |
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gamma motor neurons |
fxn to maintain sensitivity of spindle stretch by firing and causing ends of intrafusal fibers to contract, allowing info to be generated even when muscle is slack |
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when muscle is lengthened and intrafusal fibers stretched |
activity of Ia and II afferents to spinal cord where they branch branch 1 = info about motion to higher centers via ascending tracts branch 2 = interneuron to alpha motor neuron to extrafusal fibers to contract and prevent damage, and to antagonists to relax and allow contraction and to gamma motor neuron back to intrafusal fiber to keep it active and this sending signals continuously |
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GTOs |
proprioceptive mechanoreceptors in skeletal muscles at musculotendinous jxns and provides info about muscle tension and fxn to inhibit muscle in response to excessive tension |
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GTOs arranged in ___ btw muscle fibers and collagen of tendons |
series |
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what type of afferents neurons in GTOs |
Ib afferent |
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GTO records what info |
change in tension and rate of change of tension and sends to post horn of SC info to alpha motor... inhibitory to contracting muscle, excitatory to antagonist |
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types of joint receptors |
ligament receptors ruffini endings pacinian corpuscles free nerve endings |
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joint receptors |
respond to mechanical deformation of ligs and capsules |
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ligament receptors |
type Ib afferents respond to tension |
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ruffini endings (jt receptors) |
in capsule respond to extremes of joint ROM; passive > active |
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pacinian corpuscles (jt receptors) |
respond to mvmt |
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free nerve endings in jt receptors |
responds to chemical stimulus in inflammation |
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proprioception especially helpful in detecting |
size, shape, weight of object |
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all sensory systems convey what 4 basic types of info when stimulated |
modality, location, intensity, timing |
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sensory neurons |
afferent neurons; bringing info initiated in receptors in skin, skeletal muscles, tendons, joints; single myelinated or unmyelinated nerve fiber; made up of cell body and bifurcating axons |
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A-beta nerve fibers |
carry info related to touch and conscious proprioception- large diameter myelinated fast conductors |
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Ia (A alpha) Ib (A beta) , and II (A beta) nerve fibers |
carry info related to unconscious proprioception- large diameter myelinated fast conductors
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A-delta nerve fibers |
carry info related to fast pain and cool temp- medium myelinated rapid fibers |
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C-nerve fibers |
carry info related to slow pain, warm temp and itch- small unmyelinated slow conductors |
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peripheral neuropathy damage to peripheral nerve |
glove and stocking distribution |
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diabetic neuropathy |
microvascular damage; insufficient supply to peripheral nerves |
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chemotoxic neuropathy |
toxic damage to peripheral nerves |
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alcoholic neuropathy |
toxic damage to peripheral nerves and nutritional deficits particularly thiamine deficiency |
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damage/trauma/disease to/of spinal nerve |
sensory loss in dermatome distribution |
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primary/first order neurons |
all sensory info travels in these neurons from periphery to spinal cord; cell bodies outside SC in DRG; enter SC posteriorally via dorsal roots and rootlets |
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grey matter of SC, dorsal horn |
dorsal horn; sensory area |
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white matter |
ascending tracts; sensory info from periphery to brain in dorsal and lateral white matter |
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grey matter in SC arranged in |
lamina (Rexed lamina) |
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Rexed lamina |
divisions by fxn and sensory info arrives at specific areas/laminae |
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rexed lamina II
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substantia gelatinosa; important in modulation of pain sensation |
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rexed lamina III and IV |
aka nucleus proprius; conscious proprioception and touch |
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unconscious proprioception route |
spinal nerves entering at T1-L2 to dorsal horn to Clarke's nucleus to posterior spinocerebellar tract to cerebellum |
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t/f: While wefollow the large projection neurons from the periphery to the brain, there aremany interneurons at each level of the spinal cord for intercommunication |
true |
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Within the CNS a bundle of axons with the sameorigin and a common termination is called a |
tract |
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projection neurons |
The tracts (pathways) only describe thoseneurons with long axons connecting distant areas of the body. |
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conscious pathways |
fine/discriminative touch and proprioception; pain and temp (anterolateral pathways); crude touch and pressure |
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fine/discriminative touch and proprioception pathway |
dorsal columns to medial leminiscus to thalamus to cortex |
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pain and temp pathway |
anterolateral pathways |
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fast pain pathway |
spinothalamic pathway; thalamus and brain |
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slow pain pathway |
multiple pathways: spinoreticular, spinolimbic, spinomesencephalic pathways to midbrain, reticular formation, amygdala, multiple cerebral cortical areas (divergent relay pathways) |
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crude touch and pressure pathway |
venterolateral pathway; thalamus and brain |
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unconscious pathways |
unconscious proprioception via spinocerebellar pathways to cerebellum |