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321 - Physiology > Lecture 7 - Locomotion > Flashcards

Lecture 7 - Locomotion Flashcards

1
Q

Where are Lower Motor Neurons located

A

In the spinal cord and brainstem. They project out of CNS and innervate muscles

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2
Q

What is the Final Common Pathway

A

All movement is initiated through activation of LMNs. Motorneuron activity (action potential) elicits muscle contraction

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3
Q

What is the size principle

A

Small motor neurons are recruited first followed by large ones

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4
Q

Small motor neurons innervate

A

Slow motor units (Type 1 fibers)

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5
Q

Higher threshold motor neurons innervate

A

Fast motor units (Type 2a, b fibres)

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6
Q

Pathology of LMNs is associated with

A

Paresis (weakness) as muscles innervated by these LMNs are compromised

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7
Q

Tick Paralysis LMN Disease

A

Ticks release neurotoxin that affect LMN neuromuscular function where Ach & nicotinic receptors are

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8
Q

Myasthenia Gravis - disease where

A

Ach not present, but nicotinic receptors blocked

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9
Q

Can EMG be used as a diagnostic aid

A

Yes

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10
Q

EMG stands for

A

Electromyography

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11
Q

Normal EMG is generally

A

Quiet at rest

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12
Q

EMG Denervation potential can occur following

A

LMN disease/injury

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13
Q

Denervation potentials result in

A

Spontaneous action potentials known as fibrillation potentials, which do not depend on voluntary muscle activity of patient

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14
Q

Denervation/spontaneous action potentials (fibrillation potentials) may be due to

A

Ach receptors proliferation and increased responsivity to circulating levels of Ach following muscle denervation

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15
Q

How do fibrillation potentials contrast with fasciculations?

A

Fasciculations are often benign, can be visually observed, underlying causes are not clear

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16
Q

Fasciculations can be caused by

A

Stress
Low magnesium & some diseases

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17
Q

Examples of Normal EMGs

A

Insertional EMGs - caused by needle insertion, normal reaction
Resting EMGs - normal EMGs is quiet at rest
Motor unit action potential

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18
Q

Abnormal EMGs

A

Fibrillation potentials
Positive sharp waves
Fasciculations
Polysynpatic motor unit action potentials

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19
Q

Abnormal EMG - Fibrilation potentials

A

Spontaneous contraction of single motor unit

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20
Q

Abnormal EMGs- positive sharp waves

A

Associated with damage to muscle fibre membrane

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21
Q

Abnormal EMGs - fasciulations

A

Contractions are visually apparent - more than a single fibre

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22
Q

Abnormal EMGs - Polysynaptic motor unit action potentials

A

Seen during sub maximal activation-diffuse loss of MUs

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23
Q

Upper Motor Neuron (UMN) is confined to

A

The central nervous system (CNS)

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24
Q

The UMN system is divided into

A

Pyramidal and extrapyramidal system

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25
Q

Pyrimidal system (UMN) consists of

A

Neurons whose cell bodies are located in the motor cortex and project directly to the spinal cord

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26
Q

Pyramidal system is more important in

A

Primates and humans compared to domestic production animals, cats, and dogs

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27
Q

The pyramidal system provides

A

Fine control of movement

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28
Q

The extrapyramidal system consists of

A

Neurons in the brain that project directly or indirectly to the brain stem and onto the LMNs though final common pathway.

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29
Q

The Extrapyramidal system includes structures such as

A

The basal nuclei, red nucleus, thalamus, reticular formation, and much more

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30
Q

The extrapyramidal system is very important in which animals

A

Domestic animals, dogs, cats

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31
Q

The pyridimal system resides in the motor cortex, then goes to

A

Gather into a tract system then into descending fibres. Then, ipsilaterally bifurcates. Also has contralateral control still. Travels to LMN and ends there.

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32
Q

Point of ipsilateral and contralateral control

A

Plasticity after injury - can control/compensate from other side

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33
Q

Reticulospinal tract pathway

A

From medulla to interneurons and LMNs of the spinal cord

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34
Q

function of reticulospinal tract

A

Posture, initiation of walking

35
Q

Rubrospinal tract pathway

A

From red nucleus (midbrain) to LMN

36
Q

Rubrospinal cord function

A

Voluntary movement especially to large muscles. Promotes flexión, inhibits extension

37
Q

Corticospinal (pyramidal system) tract pathway

A

From primary motor cortex to LMNs in spinal cord

38
Q

Corticospinal (pyramidal system) tract function

A

Voluntary movements especially fine control. Participates in postural control.

39
Q

Vestibulospinal tract pathway

A

From vestibular nuclei to interneurons and LMNs

40
Q

Vestibulospinal tract function

A

Posture and balance control

41
Q

Corticobulbar tract pathway

A

From motor cortex to pons and medulla in brainstem

42
Q

Corticobulbar tract function

A

Multiple roles, jaw, facial muscles, swallowing, tongue

43
Q

Can interneurons be excitatory and inhibitory?

A

Yes

44
Q

What is a reflex

A

A fast involuntary motor response to peripheral stimulus

45
Q

Types of reflexes

A

Tendon-tap stretch reflex (monosynaptic reflex)
Golgi Tendon organ reflex
Withdrawal reflex
Crossed extensor reflex

46
Q

Reflex Arc components

A
  1. Receptor
  2. Afferent Pathway
  3. Integration Centre
  4. Efferent Pathway
  5. Effector
47
Q

Muscle stretch pathway - muscle stretch leads to

A

Impulses being produced by muscle spindle. Impulse travels to the spinal cord through dorsal root, where the alpha motor neuron gets excited. Then, contraction of muscle occurs

48
Q

Muscle stretch detection by muscle spindles - muscle spindles increase activity when

A

Stretched passively but decrease activity when muscles contract

49
Q

What happens to muscle spindles when the muscle is contracted?

A

Since they lie parallel to the muscle they would be silenced following a contraction- but DOES NOT HAPPEN because the interior of the spindle is kept taut by intrafusal muscle

50
Q

Gamma motoneurons are

A

A special class of motoneurons that innervate the intrafusal muscle fibres of muscle spindles. They allow contraction based on the stretch of muscle

51
Q

Gamma motoneurons innervate

A

Muscle fibres

52
Q

Gamma motoneurons allow

A

Muscle spindles to signal length changes even when muscle is shortening

53
Q

Stretch reflex can be modified by

A

Higher centres, which allows reflexes to be optimized to the ongoing behaviour

54
Q

Do you need the brain for descending control of stretch reflex?

A

No, but brain can modify or intensify response

55
Q

Can you clinically assess stretch reflex?

A

Yes

56
Q

Functional score of 0 - stretch reflex

A

Absent, interpret as LMN disease (peripheral nerves/spinal cord)

57
Q

Functional score of 1 stretch reflex assessment

A

Assessment: decreased, interpret as LMN disease (peripheral nerves/spinal cord)

58
Q

Functional score 2 assessment of stretch reflex

A

Assessment - normal; interpret - normal reflex

59
Q

Clinical assessment stretch reflex score of 3

A

Exaggerated, interpret - can occur with spinal cord trauma and other conditions

60
Q

Clinical assessment of stretch reflex score 4

A

Clonus (pulsing), interpret - UMN pathology may accompany spasticity

61
Q

Golgi Tendon Organ (GTO) Reflex

A

when muscles are contracting afferent traffic from the GTO inhibits ongoing motoneurons activity - thought to be a protective reflex

62
Q

When an animal is locomotion, the GTO reinforces what

A

Extensor muscle activity - opposite to GTO reflex function - if anyone understands this pls contact Nicole <3

63
Q

Gait

A

Pattern of footfalls or manner of walking, trotting, galloping

64
Q

Stride

A

Single coordinated movement of all limbs with a return to the starting position

65
Q

locomotion

A

The interaction between muscles and the skeleton to produce movement

66
Q

Walk

A

Provides maximum body support when speed is slow. Combination of 3 beat and 2 leg support phases. Characterized as 4 beat gait

67
Q

Trot

A

At faster speeds. Characterized by a diagonal alteration of limbs. 2 beat gait

68
Q

Canter

A

3 beat gait. 1-2-1 (hindlimb on ground, then diagonal front and hindlimb, then forelimb)

69
Q

Gallop

A

Transverse 4 beat. Used for moderate speed

70
Q

Steps in Step cycle

A

F
E1
E2
E3

71
Q

F step of walking

A

All joints flexing and paw off the ground

72
Q

E1 step of walking

A

Extension but paw is still on ground

73
Q

E2 step of walking

A

Paw on ground, ankle flexes to absorb weight

74
Q

E3 step of walking

A

Thrust phase, all joints extending.

75
Q

Which stage of locomotion changes most in stepping frequency

A

E3, or the thrust phase

76
Q

Locomotion requires

A

A rhythm & a pattern

77
Q

Are flexion and extension active at the same time when doing locomotion?

A

No

78
Q

What does the locomotor central pattern generator do

A

Decide pattern / rhythmicity of walking

79
Q

What is NOT necessary for basic pattern of locomotion

A

Sensory information from skin and muscle is not necessary
Rhythmic descending input from brain is not essential

80
Q

The neutral circuitry within spinal cord can produce a

A

Patterned locomotor pattern in the absence of patterned descending input from brain (called central pattern generator)

81
Q

2 types of central pattern generators

A

Pacemaker CPG or circuit driven CPG

82
Q

Pacemaker CPG

A

Single cell or collection of cells that are capable of oscillating based purely on intrinsic properties alone
Example- SA node in RA of heart

83
Q

Circuit-driven CPG

A

A collection of cells that produce oscillations based on the collective contribution of intrinsic, synaptic, and circuit properties

  • no clear structure, distributed throughout spinal cord

321 - Physiology (52 decks)

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