somatosensory function Flashcards

sensory pathways: explain the ascending pathways transmitting sensory information andsomatotropicorganisationwithin the pathway

1
Q

pathway of stimuli from face

A

face mechanoreceptor -> primary sensory neurone -> posterior pons -> secondary sensory neurone -> pass through midbrain -> thalamus -> tertiary sensory neurones -> somatosensory cortex

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2
Q

pathway of [innocuous mechanical] stimuli from upper limb (above T6)

A

upper limb mechanoreceptor -> [AB] primary sensory neurone -> enter posterior cervical cord via dorsal horn -> up cuneate fasciculus (ipsilateral lateral) -> enter cuneate nucleus of posterior medulla oblongata -> synapse and decussation up medial lemniscus through pons as secondary sensory neurone -> pass through midbrain -> thalamus -> tertiary sensory neurones -> somatosensory cortex

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3
Q

pathway of stimuli from lower limb (below T6)

A

lower limb mechanoreceptor -> primary sensory neurone -> posterior lumbar cord-> up gracile fasciculus (ipsilateral medial) -> enter gracile nucleus of posterior medulla oblongata -> synapse and decussation up medial lemniscus through pons as secondary sensory neurone -> pass through midbrain -> thalamus -> tertiary sensory neurones -> somatosensory cortex

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4
Q

what are size of somatotropic areas proportional to

A

density of sensory receptors in that body region (somatosensory homonculus)

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5
Q

where do pain and temperature sensations ascend within and decassate in

A

ascend within lateral spinothalamic tract (decassate in spinal cord before reaching medulla)

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6
Q

where does crude touch ascend within and decassate in

A

ascends within anterior spinothalamic tract (decassate in spinal cord before reaching medulla)

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7
Q

where do ligh touch, vibration and 2-point discrimination ascend within and decassate in

A

dorsal column (decassates in medulla)

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8
Q

testing integrity of ascending pathways using QST: spinothalamic stimuli

A

temperature and pain

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9
Q

testing integrity of ascending pathways using QST: dosral column stimuli

A

discriminative touch and 2-point discrimination

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