Anatomy 4 Ascending Tracts Flashcards Preview

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Flashcards in Anatomy 4 Ascending Tracts Deck (73)
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1
Q

What are the 3 skin sensations?

A
  1. Touch (superficial pressure or vibration)
  2. Pain
  3. Temperature
2
Q

What are the 2 musculoskeletal sensations?

A
  1. Proprioception

2. Pain

3
Q

What are the 4 types of musculoskeletal proprioception sensations?

A
  1. Muscle stretch (tension)
  2. Tendon stretch (tensions)
  3. Deep vibration
  4. Joint position (static and movement (kinesthetic))
4
Q

Describe the somato-sensory pathway starting with sensory stimulus

A
  1. Sensory stimulus
  2. Receptor
  3. Threshold stimulation
  4. AP on peripheral (distal) axon/process of pseudounipolar sensory neuron in peripheral nerve
  5. Pseudounipolar neuron soma located in dorsal root ganglia
  6. central (proximal) axon/process in dorsal root
  7. brainstem/spinal cord (white or dorsal horn gray matter)
  8. Withdrawal reflex
    or
  9. Ascending tract to
    a. lower brain (unconscious sensory input) reflex
    b. cerebral cortex (conscious perception) voluntary response
5
Q

Signal movement through the pathway is dependent on what 2 things:

A
  1. Diameter of axon

2. Degree of axon myelination

6
Q

Mechanoreceptors are sensors/receptors of peripheral system that sense what?

A
  1. Touch
  2. Pressure
  3. Stretch
  4. Vibration
7
Q

Chemoreceptors are sensors/receptors of peripheral system that sense what?

A

Viscerosensory

8
Q

Thermoreceptors are sensors/receptors of peripheral system that sense what?

A

Temperature

9
Q

Nocereceptors are sensors/receptors of peripheral system that sense what?

A

Pain

10
Q

What is a tonic receptor in the peripheral system?

Fast/Slow adapting?

A

Tonic receptor - responds as long as a stimulus is present

-Slow adapting

11
Q

What is a Phasic receptor in the peripheral system?

Fast/Slow adapting?

A

Phasic receptor - detect a change from stimulus then adapt to the changed state and stop responding before the stimulus ends
-Rapid adapting

12
Q

What are these and what do they carry and where in brain?
GVA
GSA
SSA

A

GVA - general visceral afferent (viscerosensory)
- carry unconscious signals to diencephalon
GSA - General sensory afferent (somatosensory)
- carry conscious signals to post central gyrus
SSA - Special sensory

13
Q

Where are the soma of sensory neurons located?

A

Dorsal root ganglia and cranial nerve sensory ganglia

14
Q

Sensory neuron classification:

Ia or Aa

A

large diameter, myelinated (fastest)

  • Primary muscle spindle afferents
  • Motor efferents to extrafusal muscle
15
Q

Sensory neuron classification:

Ib or Aa

A

Large diam, myelinated

  • Golgi tendon organ afferents
  • Contractile tension (force)
16
Q

Sensory neuron classification:

II or Ab

A

Medium diam, myelinated

  • Mechanoreceptors (discriminative touch, pressure, joint)
  • Secondary muscle spindle afferents (static muscle length)
17
Q

Sensory neuron classification:

III or Ad

A

Small diam, myelinated

  • Mechanoreceptors (touch)
  • Nocioception (discriminative pain)
18
Q

Sensory neuron classification:

IV or C

A

Smallest diam, unmyelinated (slowest)

  • Nocioception (inflammatory/visceral pain, thermal sense)
  • Autonomic postganglionic axons
19
Q

Skin sensation is what type of sensory?

A

Somatosensory

20
Q

What is a receptive field?

Where will you have small receptive fields and why?

A
  • Area of skin innervated by a single sensory neuron
  • Small receptor fields and greater density of sensory neurons give some body regions (finger tip) greater 2 point discrimination
21
Q

Whats the difference between receptive field and dermatome?

A

Receptive field - 1 single sensory nerve

Dermatome - 1 single spinal nerve

22
Q

Innervation of skin:

Merkel’s -

A

fine touch, closest to surface so most sensitive

23
Q

Innervation of skin:

Meissner’s -

A

fine touch and vibration

24
Q

Innervation of skin:

Pacinian -

A

Subcutaneous

fine touch and vibration

25
Q

Innervation of skin:

Hair follicle receptor -

A

Hair root plexus

26
Q

Innervation of skin:

Ruffini -

A

skin stretch, furthest from surface

27
Q

T/F:

Fine touch receptors have bad resolution of stimuli

A

False

Good resolution

28
Q

All fine touch receptors transmit signals on what fiber size?

A

Ab axons (Medium diam, myelinated)

29
Q

Innervation of skin:

Free nerve endings -

A

Course touch, pressure, tickle and itch

30
Q

Innervation of skin:

Crude localization -

A

resolution

31
Q

All course touch receptors transmit signals on what fiber size?

A

Ad

32
Q

Are fine touch or course touch fibers faster?

A

Fine touch (travel on Ab axons while course touch travels on Ad axons)

33
Q

Innervation of skin:

Nociceptors -

A
  • Free nerve endings detect extremes of mechanical, chemical, and temp stimuli (tissue damage = pain)
34
Q

What type of neurons (size) carries pain signals?

A

Ad and C neurons (slow)

35
Q

Innervation of skin:

Temperature -

A

Free nerve endings

36
Q

What type of neuron (size) carries temperature singals?

A

Ad neurons carry cooling sensation

C neurons carry heat sensation

37
Q

Proprioception is primarily determined by what type of receptors and what type of changes?

A
  1. musculoskeletal - Ruffini (stretch)
    and
  2. pressure changes associated with changing the position of body segments
38
Q

What is an intrafusal muscle fiber?

A

a muscle spindle (proprioceptor) located inside muscle parallel to muscle fibers

39
Q

What two types of muscle fibers do an intrafusal fibers consist of?

A

Nuclear chain

Nuclear bag

40
Q

Afferent Annulospiral receptor:
What axon group?
What does is detect?
Bag/chain or both?

A

annulospiral receptor

  • Group Ia sensory neuron
  • Detects dynamic length/stretch (rate of change)
  • Associated with both bag and chain intrafusal fibers
41
Q

Afferent Flower spray receptor:
What axon group?
What does is detect?
Bag/chain or both?

A

Flower spray receptor

  • Group II sensory neuron
  • Detects static length/stretch
  • Associated more with chain than bag
42
Q

What is the efferent motor stimulator of intrafusal fibers?

What does it do?

A

Gamma motor neuron

-Keep bag/chain receptors loaded

43
Q

What occurs when muscle spindle if a muscle is stretched at a joint?

A

Muscle spindle is stretched -> sends afferent signals to brain regarding change in length -> brain takes in signal to determine whether body part at that joint is moving and where it is in space (proprioception)

44
Q

What type of motor neuron contracts whole muscle?

A

-Alpha motor neurons stretch whole muscle (extrafusal fibers)

45
Q

What happens to muscle spindle fibers when whole muscle contracts?

A

-Muscle spindle fibers (intrafusal) will also contract via gamma motor neurons to keep spindle stretched/tense so it will remain sensitive when when whole muscle is shortening during contraction

46
Q

T/F:
Muscle spindles only capable of Phasic signaling via type Ia (annulospiral) and II (flower spray) afferent sensory neurons

A

False

Capable of phasic and tonic signaling

47
Q

What are golgi tendon organs?

What will it inhibit in muscle?

A
  • Acts as proprioception
  • Series arrangement of nerve endings in the dense regular CT of the tendon (sensitive to changes in tension/stretch of tendon)
  • Part of reflex that inhibits muscle contraction to reduce stretch on muscle/tendon
48
Q

What type of sensory neuron (size) is golgi tendon organs?

A

Type Ib afferent

49
Q

What are joint receptors?

A

-Respond to mechanical deformation of joint capsule and ligaments

50
Q

What are the 4 types of joint receptors and what do they do?

A
  1. Paciniform - movement
  2. Ruffini - indicate end range and passive movement
  3. Free nerve endings - pain from inflammation
  4. Ligament receptors - tension (stretch) receptors
51
Q

What is proprioception and receptors?

A
-Awareness of joint position
Results from:
1. Muscle spindles
2. Joint receptors 
3. Cutaneous mechanoreceptors
52
Q

What is the difference between a tract and a pathway?

A

Tract - bundle of axons in CNS with common origin and destination
Pathway - includes peripheral neuron that delivers information to the CNS tract and carries information from tract to final destination

53
Q

T/F:

Only short axons are included in pathway descriptions

A

False: only neurons with long axons (projection neurons) are included in pathway descriptions
-Pathways also contain interneurons that interconnect pathways

54
Q

What is a conscious pathway?

A

Ends in cerebral cortex

55
Q

What is a divergent pathway?

A

branch to end at many CNS locations for both conscious and unconscious perception

56
Q

What is an unconscious pathway?

A

End at brain locations below the cerebral cortex (brainstem, cerebellum, diencephalon, limbic)

57
Q

What is a loop pathway?

A
  • Neural connection between a receptor and effector

- Includes sensory pathway, CNS control center, and motor pathway

58
Q

What is the difference between high fidelity and low fidelity?

A

High - pinpoint location of origin

Low - signals have a general origin

59
Q

What is discriminative information?

A

Allows for precise identification of stimuli

60
Q

What is required for high fidelity signals?

A

Somatotopic organization

61
Q

What does slow pain result from?
Is slow pain localizable?
What fibers carry slow pain?
Where is slow pain’s destination?

A
  • Results from tissue damage
  • NOT localizable
  • Carried by C fibers
  • Destination:
    1. Insula
    2. Associative sensory cortex of parietal lobe
62
Q

Is divergent pathway conscious/unconscious or both?

What is the medial pain system for divergent pathways?

A

Divergent pathways - both conscious and unconscious

Medial pain system - for pain modulation, motivational, withdrawal, arousal, and autonomic responses to pain

63
Q

Nocireceptors become more/less sensitive with repetitive stimulus of the medial pain system of divergent pathways?

A

More sensitive

64
Q

Describe divergent pathways of medial pain system:
Somatotopic?
Localizable?
# of Neurons?

A

Not somatotopic or localizable

Variable number of neurons

65
Q

What NT does divergent pathways of medial pain system use?

A

Substance P at synapse in dorsal horn of Lamina I, II, V

66
Q

Divergent neurons:
Spinomesencephalic -
What does it carry and to where?
What part of spinal cord carries descending?

A

Reflex movement tract -> superior colliculus

  1. Turn head to position eye on pain source
  2. Activate descending neurons that modulate pain sensation
    - Periaquiductal gray found in mesencephalic: descending pain modulation
67
Q

Divergent neurons:

Spinoreticular -

A

Intensity tract -> reticular formation such as raphe nucleus, locus ceruleus, to modulate pain sensation to thalamus

68
Q

Divergent neurons:

Spinolimbic -

A

Conscious emotional response tract -> anterior cingulate cortex (links pain sensation to emotional response, negative feeling toward pain)
-> posterior insula: pain sensation

69
Q

Unconscious pathways general:

Carry what from where to where to do what?

A

Carry proprioceptive and feedback info about activity in motor tracts (interneuron links) to cerebellum to adjust (refine) conscious movement

70
Q
Unconscious pathways:
Posterior spinocerebellar pathway - 
Somatotopic?
Localizable?
# of Neurons?
Crossed?
A

2 Neuron pathway carrying high fidelity somatotopic information from the lower body to cerebellar cortex on ipsilateral side (uncrossed)

71
Q
Unconscious pathways:
Cuneocerebellar pathway - 
Somatotopic?
Localizable?
# of Neurons?
Crossed?
A

2 Neuron pathway carrying high fidelity somatotopic info from upper body to cerebellar cortex in ipsilateral side (uncrossed)

72
Q
Unconscious pathways:
Anterior Spinocerebellar tract
Somatotopic?
Localizable?
# of Neurons?
Crossed?
A

1 Neuron pathway to provide cerebellum feedback from spinal cord ventral horn interneurons to monitor activity of lower body

  • Crossed
  • Low fidelity
73
Q
Unconscious pathways:
Rostrospinocerebellar tract
Somatotopic?
Localizable?
# of Neurons?
Crossed?
A

1 neuron pathway to provide cerebellum feedback from spinal cord interneurons and motor activity of upper body

  • Ipsilateral
  • Low fidelity