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Phase 1 - S4 Nervous System > Sensation > Flashcards

Flashcards in Sensation Deck (27)
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1

what are the modalities sensed by the spinothalamic system

pain, temperature and crude touch

2

what are the modalities sensed by the dorsal column

fine touch, 2 point discrimination, proprioception and vibration

3

where are the cell bodies for primary sensory neurones found

in the dorsal root ganglion

4

which sensory neurones decussate

secondary

5

where do sensory neurones decussate

spinothalamic = ventral white commissure
dorsal column = medulla

6

where are the cell bodies for the secondary sensory neurones

spinothalamic = dorsal horn
dorsal column = medulla

7

where are the cell bodies for the tertiary sensory neurones

thalamus

8

in the spinothalamic tract are fibres from higher regions added medially or laterally

medially

9

in the spinothalamic tract are the lower fibres more medial or lateral

lateral

10

in the dorsal column tract are fibres from higher regions added more medially or laterally

laterally

11

in the dorsal column tract are the lower fibres more medial or lateral

medial

12

where do the primary neurones of lower fibres in the dorsal column synapse

gracile nucleus

13

where do the primary neurones of the upper fibres in the dorsal column synapse

cungate nucleus

14

what is the name of the pathway of the secondary neurone in the dorsal column tract

medial lemniscus pathway

15

what are rapidly adapting receptors

receptors which initially give a higher frequency of action potentials but then slows down the rate of frequency

16

give an example of a rapidly adapting receptor

mechanoreceptors

17

what are slowly adapting receptors

where the frequency of action potentials given off by the receptor remains the same

18

give an example of a slowly adapting receptor

pain receptor

19

what happens to the acuity with a large receptive field

it decreases - therefore, there a less distinct outlines of dermatomes as theres no overlap

20

what is the receptive field

the regions containing receptors feeding back to one primary neurone

21

describe the homunculus

lower regions of the body are projected medially on the cortex but the upper regions are projected laterally onto the cortex

22

what happens if there is a lesion to the dorsal roots

you will lose all modalities at that level

23

when does brown-sequard syndrome occur

when there is damage to one half of the spinal cord only

24

describe the effect of brown-sequard syndrome

- anaesthesia across the single dermatome
- ipsilateral loss of dorsal column modalities at that level and below
- contralateral loss of spinothalamic modalities at that level and below

25

what are the name of the primary neurones involved in the sensation of pain

C fibres

26

how can the sensation of pain be inhibited

- mechanoreceptors
- heat
- opiates
- descending projections from the brain

27

describe how mechanoreceptors inhibit pain

activating the mechanoreceptors by rubbing them excites inhibitory enkephalinergic interneurones which inhibit pain through activating A fibres