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Flashcards in Ascending Sensory pathways 1 Deck (57):
1

What are somaesthetic pathways?

perception of bodily sense - pain, temperature, touch and position

2

What is a spinothalamic pathway?

responds to pain, temp and some touch

3

What is a dorsal column pathway?

responds to fine, precise touch, vibration and position.

4

What is proprioception?

position awareness

5

What two things does the somaesthetic pathway involve?

-body
- perception

6

From where are different types of modalities of information carried to the brain in the somaesthetic pathway? (4)

1. Skin
2. Mucus membranes
3. Joints
4. Muscles

7

How is each modality detected in somaesthetic pathway?

specific sensory receptors/ specialised nerve endings

8

What 2 groups does somaesthetic modalities fall into?

1. Essential for survival - Spinothalamic pathway
2. That increase detail - Dorsal column pathway

9

What modalities are essential to survival?

pain, temperature, some touch and pressure

10

What types of fibres are modalities that are essential for survival/spinothalamic pathway carried?

thin, small diameter, poorly myelinated or unmyelinated fibres

11

What is conduction like in modalities that are essential for survival/ spinothalamic pathway?

slow

12

What modalities increase detail/ dorsal column pathway?

2 point discrimination and vibration, proprioception

13

What type of fibres carry modalities that increase detail/ dorsal column pathway?

large diameter, heavily myelinated

14

What is conduction like in modalities that increase detail/ dorsal column pathway?

fast

15

Which side of the central gyrus of the brain is information from the right side sensed?

left central gyrus

16

How many neurones are involved in the general sensory pathway?

3 neurone chain

17

What is in the thalamus?

VPL - ventral posteral nucleus/ Posterior ventral nucleus

18

What is the 1st order neurone?

- pseudo unipolar cell body
- in sensory ganglion
- DRG
- centre is ipsilateral

19

What is the 2nd order neurone?

- axon crosses midline
- ascends to ventral posterior nucleus in thalamus

20

What is the 3rd order neurone?

- axon projects to post central gyrus - parietal lobe

21

Where do the cell bodies of the 1st order neurons reside in?

dorsal root ganglia (PNS)

22

Where do the cell bodies of 2nd order neurons reside in?

CNS ipsilateral gray matter

23

Where do axons of the 2nd order neurone cross and what do they ascend to?

crosses the midline

ascend to thalamus

24

Where do the cell bodies of 3rd neurone reside in and where do the axons project to?

thalamus

axons project to somatosensory cortex

25

What pathways are somatotopic?

sensory pathways

26

How can synaptic transmission from 1st, 2nd and 3rd neurone be modified?

- neurones not simple relay
- modified by other inputs - descending pathways or convergence/divergence

27

What is the medial surface of the brain's hemisphere supplied by and what can damage result in?

Anterior cerebral artery

damage to certain features on somatotopic map on post-central gyrus

28

What is a converging circuit?

several presynaptic neurons that stimulate a single postsynaptic neuron

29

What is a diverging circuit?

a single presynaptic neurone stimulating several post-synaptic neurone

30

What are the two major types of fibre tracts?

ascending fibre tracts

descending fibre tracts

31

Is the dorsal column ipsilateral or contralateral?

ipsilateral

32

What information does the dorsal column interpret?

joint position sense and vibration sense

33

When does the dorsal column cross the midline?

- won't cross immediately

-crosses over at the medulla

34

Is the spinothalamic pathway ipsilateral or contralateral?

contralateral

35

When does the spinothalmic pathway cross the midline?

immediately

36

In spinothalamic pathway where does the synapse cross over the midline?

at a very specific place

37

In the spinothalamic pathway where is the 1st neurone cell body?

In dorsal root ganglia

38

How and where does the 1st neurone contact the 2nd neurone in the spinothalmic pathway?

Fibres ascend 1-2 segments then contacts in dorsal grey horn

39

Where does the second neurone cross the midline in the spinothalamic pathway?

in ventral white commissure

40

In the spinothalamic tract where does the 2nd neurone fibres ascend to?

thalamus

41

Where does the spinothalamic tract change it's name?

At the levels of the brainstem

Spinal lemiscus

42

Where is the 1st neurone cell body in the dorsal column pathway?

Dorsal root ganglion

43

Where do the 2nd neurone cell body ascend?

In one of the ipsilateral dorsal column

44

Where does the gracile fascicle run?

whole length of the spinal cord

45

Where does the cuneate fascicle run?

above T6 only

46

In the dorsal surface on the brain stem what receives ascending sensory tracts from the spinal cord and what are these a part of?

medulla

- the dorsal column pathway

47

What types of sensations does the dorsal column pathway pick up?

discriminatory touch

position sense

48

Where does the 1st neurone ascend to synapse with the 2nd neuron in the dorsal column pathway?

The cuneate or gracile nucleus

49

Where does the 2nd neurone cross the midline in the dorsal column pathway?

internal arcuate fibres

50

Where to the fibres in the dorsal column pathway ascend in and to?

Medial lemniscus to thalamus

51

What is somatotopically organised?

medial leminiscus - collection of fibres that pass through the brainstem

52

Which hemisphere do both pathways project to?

to the opposite hemisphere

53

Where do fibres carrying pain an temperature travel in the cord? (spinothalamic pathway)

Contralaterally

54

Where do fibres carrying pain and temperature (spinothalamic pathway) cross?

at the level of the spinal cord entry

55

Where do fibres carrying discriminative touch and proprioception travel?

ipsilateral in the cord

56

How many neurons does the dorsal column and spinothalamic pathway use?

3 neurons

57

Examples of different modalities

1. temp
2. pain
3. pressure