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Flashcards in Chapter 6 Deck (94):
1

Somatosensation:

sensory information form the skin and musculoskeletal system

2

Superficial or cutaneous

information from the skin

3

Proprioception

information from the musculoskeletal system

4

What is the speed of information processing determined by?

Diameter of the axons
Degree of axonal myelination
Number of synapses in the pathway

5

Sensory information:

nerve impulses generated from original stimuli

6

Sensation

awareness of stimuli from the senses

7

Where does interpretation of sensation into meaningful forms occur?

cerebrum

8

What are mechanoreceptors?

respond to the mechanical deformation of the receptor by touch, pressure, stretch, or vibration

9

What are chemoreceptors?

respond to substances released by cells, including damaged cells after injury or infection

10

What are thermoreceptors?

transmit information regarding heat or cold

11

What is included in sensation from the skin?

touch
pain
temperature

12

Pain

nociceptors which are free nerve endings

13

Temperature:

also free nerve endings that responds to warmth or cold within a non-damaging temperature range

14

How is touch categorized?

fine
coarse

15

Fine touch:

includes a variety of receptors and subsensations

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Coarse touch:

mediated by free endings throughout the skin

17

What do cutaneous receptors respond to?

touch, pressure, vibration, stretch, noxious stimuli, and temperature

18

What are receptive fields?

areas of skin innervated by a single afferent neuron
smaller distally and larger proximally

19

Where are somatosensory peripheral neurons?

Are outside the spinal cord in the dorsal root ganglia (DRG) or brain in the cranial nerve (CN) ganglia

20

How many axons do peripheral sensory neurons have?

2
distal
proximal

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Distal peripheral nerve axons:

Conduct messages from the receptor to the cell body

22

Proximal peripheral nerve axons

Project from the cell body into the spinal cord or brainstem

23

A-alpha (Ia and II) axon
function
receptor type

proprioception
muscle spindle

24

A beta axon
function
receptor type

touch
merkel, meissner, pacinian and ruffini

25

A delta
function
receptor type

pain, temperature
free nerve endings

26

C fibers
function
receptor type

pain, temperature, itch
free nerve endings (unmyelinated)

27

What does the muscle spindle do?

muscle can feedback information to the CNS on its state of elongation. This is achieved by a special sensory organ at the core of the muscle called

28

What are the two types of intrafusal fibers?

nuclear bags fibers
nuclear chain fibers

29

What are nuclear bag fibers?

clumps of nuclei

30

What are nuclear chain fibers?

nuclei arranged in single file

31

What are the two different sensory endings?

primary
secondary

32

Primary endings:

wrap around the central region of each intrafusal fiber.
type Ia neuron

33

Secondary endings:

end mainly on nuclear chain fibers adjacent to the primary endings
type II afferent

34

Where are intrafusal fibers contractile?

only at ends; central region cannot contract

35

What is muscle length singled by?

type Ia and II afferents

36

What is velocity?

change in muscle length signaled by only type Ia afferents

37

Information about Golgi Tendon Organs is transmitted to the spinal cord by what fibers?

type Ib

38

What do mechanoreceptors in and around joints respond to?

mechanical deformation of the capsule and ligaments

39

Type Ia axon

Quick stretch information from the muscle spindle

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Type Ib axon

Tendon or ligament tension

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Type II axon

Maintained muscle stretch or joint movement

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Type A-beta axon

Touch, vibration, skin stretch, or pressure

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Type A-delta or C

Pain, temperature, itch, or tickle

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What is a tract?

bundle of axons with the same origin and a common termination

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What is high fidelity?

provide accurate details regarding the location of the stimulation

46

What are the three pathways bringing information to the brain?

Conscious relay
Divergent
Unconscious relay

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What do conscious relay pathways do?

Transmit information to many locations in the brainstem and cerebrum and use pathways

48

How is information transmitted in conscious relay pathways?

high fidelity
make fine distinction about stimuli

49

What are the two routes pathways to consciousness travel upward in the spinal cord?

dorsal columns
anterolateral tracts

50

What is discriminative touch?

refers to the localization of touch and vibration and the ability to discriminate between two closely spaced points touching the skin

51

Pathway of discriminative touch?

DCML

52

What is conscious proprioception?

awareness of the movements and relative position of body parts

53

Pathway of conscious proprioception?

DCML

54

What is stereognosis?

the ability to use touch and proprioceptive information to identify an object

55

Pathway of sterognosis?

DCML

56

Primary neuron in pathway for discriminative touch and conscious proprioception?

conveys information from the receptors to the medulla

57

Secondary neuron in pathway for discriminative touch and conscious proprioception?

conveys information from the medulla to the thalamus

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Tertiary neuron in pathway for discriminative touch and conscious proprioception?

conveys information from the thalamus to the cerebral cortex

59

Primary neurons of DCML include:

Many collateral branches entering the gray matter

60

Secondary neurons of DCML include:

Cell bodies located in the nucleus gracilis or cuneatus
Axons that cross the midline as the internal arcuate fibers, then ascend to the thalamus

61

Tertiary neurons of DCML include:

Those that connect the thalamus to the sensory cortex

62

What does anterolateral tract transmit?

discriminative information about pain, temperature, and course touch

63

What are heat and cold detected by?

specialized free nerve endings of small myelinated and unmyelinated neurons

64

What do A-delta fibers carry?

impulses produced by cooling

65

What do C-fibers carry?

information regarding heat

66

What is fast pain

(spinothalamic pain) is the initial and immediate sharp sensation that indicates the location of the injury

67

What is slow pain?

(spinolimbic pain) is the dull, throbbing ache following fast pain that is not well localized

68

Fast, localized pain, what system?

lateral pain system

69

Primary neuron in fast pain:

bring information into the dorsal horn of the spinal cord

70

Secondary neuron in fast pain:

cross the midline and project from the spinal cord to the thalamus.

71

Tertiary neurons in fast pain:

project from the thalamus to the cerebral cortex

72

In the anterolateral column, second order neuron:

ascends contralaterlly
cross midline at spinal cord

73

In the DCML, first order neuron

ascends ipsilaterally

74

In the DCML, second order neurons

crosses midline at medulla

75

Slow pain impulses travel:

C fibers which are smaller, unmyelinated axons

76

How is aching pain transmitted?

via divergent pathways to many locations in the brainstem and cerebrum
medial pain system

77

Where is the first neuron in the medial pain system?

resides in the dorsal root ganglion and has a small, unmyelinated C fiber

78

What is the activity of medial pain system?

elicits affective, motivational, withdrawal, arousal, and autonomic responses

79

What are the three tracts that axon of ascending projection neurons reach the midbrain, reticular formation and limbic areas?

spinomesencephalic
spinoreticular
spinolimbic

80

What are the two areas of the spinomesencephalic tract in the midbrain that carry noceiceptive information?

periaqueductal gray
superior colliculus

81

The periaqueductal gray is part of what system?

descending pain control system

82

What is the reticular formation?

A neural network in the brainstem that includes the reticular nuclei and their connections

83

What does the reticular formation do?

Modulates arousal, attention, and sleep-waking cycles

84

What do axons of the spinolimbic tract do?

transmit slow pain information to the medial and intralaminar nuclei in the thalamus

85

What is the trigeminoreticulolibic pathway?

Slow pain information is transmitted via this pathway from the face
C fibers in trigeminal nerve

86

What do unconscious relay tracts do?

Transmit information from proprioceptors and information about activity in spinal interneurons.
-relay information critical for adjusting movements
-cerebellum

87

What is the posterior spinocerebellar pathway?

Transmits information from the legs and the lower half of the body

88

What is the cuneocerebellar pathway?

Begins with primary afferents from the arm and upper half of the body; the central axons travel via the posterior columns to the lower medulla

89

What are internal feedback tracts?

Tracts monitor the activity of spinal interneurons and of descending motor signals from the cerebral cortex and brainstem

90

What are the two types of internal feeback tracts?

anterior spinocerebellar
rostrospinocerebellar

91

What does the anterior spinocerebellar tract do?

Transmits information from the thoracolumbar spinal cord

92

What does the rostrospinocerebellar tract do?

Transmits information from the cervical spinal cord to the ipsilateral cerebellum

93

Where does the information in the spinocerebellar tract come from?

the proprioceptors, spinal interneurons, and descending motor pathways

94

What does information that does not reach conscious awareness do?

contributes to automatic movements and postural adjustments