Somatosensory Systems Flashcards

1
Q

Are somatosensory systems ascending or descending

A

Ascending

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2
Q

True or False:

Dorsal root ganglia are pseudounipolar

A

True

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3
Q

What are located in the dorsal root ganglia

A

Cell bodies

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4
Q

How many branches does the axon have

A

2

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5
Q

What are the 2 branches of the axon

A

One projects to the periphery and the other projects to the spinal cord or brainstem

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6
Q

What do specialized terminals on peripheral branch do

A

Convert environmental energy into nervous system signals

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7
Q

The distal/peripheral section of the axon may either be what (2)

A
  1. Bare nerve ending

2. Encapsulated by a structure that helps relay specific information to nerve

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8
Q

Why can’t you perceive the shirt on your back

A

Adaption

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9
Q

True or False:

Tactile receptors of the skin exist in different densities in different locations on your body

A

True

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10
Q

What is the distance between two tactile stimuli at which the two are just discerned to be separate

A

Simultaneous spatial threshold

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11
Q

True or False:

Pain always adapts

A

False

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12
Q

What are the 5 types of receptors

A
  1. Cutaneous and subcutaneous mechanoreceptors
  2. Muscle and skeletal mechanoreceptor
  3. Nociceptors
  4. Thermal receptors
  5. Itch receptors
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13
Q

Large diameter myelinated sensory nerve fibers muscles fiber, cutaneous nerve, diameter, and conduction

A

Muscle fiber: I
Cutaneous nerve: Aa
Diameter: 12-20 um
Velocity: 72-120 m/s

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14
Q

Medium diameter myelinated sensory nerve fibers muscles fiber, cutaneous nerve, diameter, and conduction

A

Muscle fiber: II
Cutaneous nerve: Ab
Diameter: 6-12 um
Velocity: 36-72 m/s

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15
Q

Small diameter myelinated sensory nerve fibers muscles fiber, cutaneous nerve, diameter, and conduction

A

Muscle fiber: III
Cutaneous nerve: Ad
Diameter: 1-6 um
Velocity: 4-36 m/s

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16
Q

Unmyelinated sensory nerve fibers muscles fiber, cutaneous nerve, diameter, and conduction

A

Muscle fiber: IV
Cutaneous nerve: C
Diameter: 0.2-1.5 um
Velocity: 0.4-2 m/s

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17
Q

Type I is the main neuron for what

A

Proprioception (muscle and joint activity)

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18
Q

Ab is the main neuron for

A

Touch (mechanoreceptors)

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19
Q

C fibers conduct what (2)

A
  1. Poorly localized, dull, aching, pain

2. Itch

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20
Q

What do large diameter myelinated fibers innervate (2)

A
  1. Muscle spindle receptors

2. GTO (muscle length and contractile force

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21
Q

What do medium diameter myelinated fiber innervate

A

Secondary spindle endings and receptors in joint capsules (proprioception)

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22
Q

What do small diameter myelinated and unmyelinated fibers innervate

A

Muscle and joint pain

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23
Q

What is a sensory region of the skin and deeper tissues innervated by a given nerve root

A

Dermatome

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24
Q

True or False:

The dermatomes are largely overlapping in the thoracic region

A

True

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25
Q

Somatotopy is maintained in what (3)

A
  1. Spinal cord
  2. Brainstem relay nuclei
  3. Cortex
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26
Q

What does the somatotopy aid in

A

Localization of lesions

27
Q

What are the 2 main somatosensory pathways

A
  1. Dorsal column (medial lemniscus pathway)

2. Anterolateral pathway

28
Q

True or False:

Both main somatosensory pathways share touch

A

True

29
Q

What does the dorsal column (medial lemniscus pathway) sense (3)

A
  1. Fine discriminative touch
  2. Proprioception
  3. Vibration
30
Q

What does the anterolateral pathway sense (3)

A
  1. Pain
  2. Temperature
  3. Crude touch
31
Q

What is crude touch

A

You know they are touching you but you don’t know where

32
Q

What is discriminative touch

A

You can discriminate place and intensity of touch

33
Q

Where does the dorsal column cross

A

In medulla

34
Q

Where does the anterolateral pathway cross

A

Crosses right away in the cord

35
Q

Where does damage occur in the dorsal column pathway

A

Ipsilateral

36
Q

Where does damage occur in the anterolateral pathway

A

Contralateral

37
Q

What is the first order neuron

A

Cell body in DRG and carries sensory impulse from receptor to CNS

38
Q

What is the second order neuron

A

These fibers decussate and carry info to the thalamus

39
Q

Where can the second order neurons be (2)

A
  1. Spinal cord

2. Brainstem

40
Q

What is the third order neuron

A

Carries info from thalamus to post central gyrus (primary somatosensory cortex)

41
Q

True or False:

Cuneate equals wedge shaped

A

True

42
Q

True or False:

Gracile equals thin

A

True

43
Q

True or False:

Fasciculi equals bundle (subset) of a funiculus

A

True

44
Q

True or False:

There is no sensory to the face in the spinal cord

A

True

45
Q

Where does sensory of the legs come from for the dorsal column pathway anatomically in the spinal cord

A

Medial

46
Q

Where does sensory of the legs come from for the anterolateral system anatomically in the spinal cord

A

Anterolateral

47
Q

Where does the first order neuron travel for the dorsal column

A

Ascends in posterior column in the fasciculus gracile or cuneatus

48
Q

What sensory info travels in the fasciculus gracile and cuneatus

A

Gracile: Lower body
Cuneatus: Upper body (T6 and above)

49
Q

Where do the fibers of the first order neuron of the dorsal column synapse

A

Caudal medulla

50
Q

Where does the second order neuron of the dorsal column decussate

A

In the medulla

51
Q

What does the second order neuron of the dorsal column decussating form

A

Medial lemniscus

52
Q

Where does the second order neuron of the dorsal column synpase

A

On the ventral posterior lateral (VPL) nucleus of the thalamus

53
Q

Where do the third order neurons of the dorsal column travel

A

Ascend through the posterior limb of the internal capsule to the post central gyrus

54
Q

True or False:

The thalamus is a collection of cell bodies and is gray matter

A

True

55
Q

True or False:
Most afferents do not meet their 1st synapse until they arrive at the nucleus gracilis or nucleus cuneatus in the lower medulla

A

True

56
Q

What is difficulty recognizing a written number or letter traced on the skin after parietal damage

A

Agraphesthesia

57
Q

What is the inability to identify objects by manipulation with eyes closed that results from a focal cortical lesion of the parietal lobe posterior association area or dorsal column

A

Astereognosis

58
Q

What is a reduction in sensitivity on one side of the body

A

Hemihypesthesia

59
Q

What may a person with hemihypesthesia not be able to perceive

A

Being lightly touched on one side but has normal function on the other side of the body

60
Q

What size fibers are in the anterolateral spinothalamic pathway

A

Small myelinated and unmyelinated

61
Q

Where do the fibers of the anterolateral spinothalamic pathway synapse

A

Dorsal horn

62
Q

Where do the fibers of the anterolateral spinothalamic pathway decussate

A

Immediately at the level they enter

63
Q

Where do the fibers of the anterolateral spinothalamic pathway travel in the cord

A

Anterolateral part to the ventral posterolateral nucleus of thalamus

64
Q

Where do the tertiary fibers of the anterolateral spinothalamic pathway travel

A

From thalamus to the posterior limb of the internal capsule to the post central gyrus