3.1+2 Somatosensory Flashcards Preview

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Flashcards in 3.1+2 Somatosensory Deck (53):
1

What is the butterfly shaped structure in the spinal cord?

Grey matter

2

What are the two major pathways involved in somatic sensory perception?

Dorsal columnar-medial lemniscal pathway

Spinothalamic tract

3

What are the two fasciculi in the dorsal column?

Fasciculus gracilus

Fasciculus cuneatus

4

What is a sensory modality?

Distinct mode of sensation

e.g. touch vs pain

5

Is stickiness a modality?

No, it is a mixture of modality

Pressure, stretch, pain etc

6

Which modalities run through the dorsal column system?

Conscious proprioception

Two-point discrimination

Vibration sense

Fine Touch

7

Which modalities run through the spinothalamic tract?

Pressure/Crude Touch

Pain

Temperature

8

Where is the cell body of a primary sensory neurone located?

Dorsal root ganglion

9

What is a spinal nerve?

Both sensory and motor fibres

Formed by dorsal and ventral root coming together

10

What supplies a single myotome and dermatome?

Spinal nerve

11

What are the two different types of sensory neurone units?

Rapidly adapting

Slowly adapting

12

What is the feature of rapidly adapting sensory neurones?

Good at detecting changes in activation of the receptor

13

Give an example of a rapidly adapting sensory neurone in action

Cutaneous mechanoreceptors

Detect pressure when you sit

Adapt rapidly and slow down in firing

You soon dont feel chair

14

What is the feature of slowly adapting sensory neurones and give an example of when they might be useful?

Wont really change in its firing

Pain receptors, dont want them to stop until stimulus is removed

15

What is meant if a neurone has a 'low acuity'?

Area sensed by the sensory neurone is large

16

What is the relationship between acuity and the size of a receptive field?

Inversely proportional

17

Why are there fuzzy boundaries to dermatomes?

Because receptive fields can overlap

18

What is the receptive field?

The region of the skin detected by ONE sensory neurone

19

What do the 'laws' of primary sensory neurones of somatosensory pathways dictate?

Cell body in DRG

Receives information from receptor

Within CNS - neurone remains IPSILATERAL to cell body

20

What do the 'laws' of secondary sensory neurones of somatosensory pathways dictate?

Second order neurone DECUSSATES to the CONTRALATERAL side

Cell body in dorsal horn of medulla

21

What do the 'laws' of tertiary sensory neurones of somatosensory pathways dictate?

Projects to primary sensory cortex

Cell body in Thalamus

22

Where is the primary sensory Cortex located in the brain?

Post central gyrus

23

From a dermatomal pattern, to what do the sensory fibres reorganise in the cortex?

Homuncular pattern

24

How does the Dorsal Column pathway map to the tract in the spinal cord?

LOWER BODY

to

MEDIAL PORTION of tract

25

How does the spinothalamic tract map to the tract in the spinal cord?

LOWER BODY

to

LATERAL/SUPERFICIAL part of tract

26

How do sensory neurones add to the DCML pathway?

Add onto the OUTSIDE

27

How do sensory neurones add to the Spinothalamic tract?

Add to the INSIDE

28

How is the upper half of the body represented in the DCML pathway?

On the OUTSIDE

29

How is the upper half of the body represented in the ST?

On the INSIDE

30

What does the medial lemniscus connect?

Gracile and Cuneate nuclei

TO

Thalamus

31

In which nucleus do first order somatosensory neurones of the lower body synapse?

Gracile

32

In which nucleus do first order somatosensory neurones of the upper body synapse?

Cuneate

33

Where are the gracile and cuneate nuclei found?

Medulla oblongata

34

Where do first order DCML neurones synapse?

In the medulla

35

Where do second order DCML fibres synapse?

In the thalamus

36

Where is the lower body represented on the homunculus?

Medial

37

Where is the upper body represented on the homunculus?

Lateral

38

Is there crossing over of third order DCML fibres?

Not really

39

What is another name for the spinothalamic tract?

Anterolateral system

40

Which side do ISOLATED DCML lesions affected?

ISPILATERAL signs

Below the lesion

41

Which side do isolated spinothalamic tract lesions affect?

CONTRALATERAL signs

Below the lesion

42

How do spinothalamic sensory neurones decussate?

Enters dorsal horn of grey matter and synapses

Decussates via the ventral white commissure fibres and ascend in the ST

43

What are commissure fibres?

Fibres which connect the two halves of the CNS

44

Which order of somatosensory neurone always performs the decussation?

Second order

45

Where do the second order neurones of the spinothalamic tract synapse?

Thalamus

46

Where the ascending somatosensory pathways located, white or grey matter?

White matter

All pathways in white?

47

What has been damaged in Brown-Sequard Syndrome?

Complete cord hemisection

Destruction of single cord segment

48

What are the signs experienced in Brown-Sequard Syndrome?

COMPLETE anaesthesia affecting the corresponding dermatome

Ispsilatereal loss of DCML modalities BELOW lesion

Contralateral loss of ST modalities BELOW lesion

49

Through which somatosensory system does pain run through?

Spinothalamic tract

50

What is the major primary afferent fibre for pain?

C fibres

51

What do A fibres do?

Carry impulses from mechanoreceptors in the skin

52

How does rubbing a painful area, relieve the pain?

Mechanoreceptors detect rubbing

Activates inhibitory neurones

Inhibits second order neurones

53

Besides rubbing the affected area, what else can inhibit the transmission of pain signals?

Heat

Descending control of pain