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Neurophys II/III > Motor control pt. 1 > Flashcards

Motor control pt. 1 Flashcards

1
Q

What major areas of the CNS are involved in motor control?

A 
Cerebral cortex
Basal ganglia
Thalamus
Cerebellum
Brain stem
Spinal cord
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2
Q

What are the 3 divisions of the motor cortex?

A

Primary motor cortex, premotor area, supplemental motor area.

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3
Q

What kind of arrangement is the motor cortex made up of? What two areas/functions receive the greatest representation?

A

Somatotropic arrangement. The hands and speech.

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4
Q

T/F

+ of a neuron in the motor cortex results in the contraction of a single muscle.

A

False: stimulation of a neuron in the motor cortex results in gross movement.

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5
Q

The premotor cortex occupies what aspect(s) of the primary motor cortex? It is below what structure?

A

The anterior and lateral portions. It lies below the supplemental area.

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6
Q

The premotor area projects to what 2 areas?

A

The primary motor cortex, basal ganglia.

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7
Q

The supplemental motor area lies mainly in what fissure?

A

The longitudinal fissure

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8
Q

The supplemental area fxns in concert with the premotor area to carry out what 4 functions?

A

Attitudinal movements
Fixation movements
Positional movements of head and eyes
Background for finer motor control of arms/hands

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9
Q

The corticospinal tract originates from 3 major areas, what are they, and how much representation does each area have?

A

Primary motor cortex (30%)
Premotor and supplemental areas (30%)
Somatic sensory areas (40%)

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10
Q

The corticospinal tract descends via what structure of the internal capsule?

A

The posterior limb (between caudate and putamen).

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11
Q

What part of the medulla is formed by the corticospinal tract?

A

The pyramids

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12
Q

Most fibers in the corticospinal tract cross midline and form what? Others stay ipsilateral and form what?

A

Crossing fibers - lateral corticospinal tract. Ipsilateral fibers - ventral corticospinal tract.

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13
Q

In spinal preparation, where is the cut and what is the result?

A

All tracts are cut, separating cord from the brain. Flaccidity (flaccid, floppy paralysis) results.

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14
Q

In decerebrate preparation, where is the cut and what is the result?

A

transection at mid-collicular level. Extensors become tonically hyperactive “decerebrate rigidity”.

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15
Q

In decorticate preparation, what is damaged and what is the result?

A

Destruction of the cerebral cortex, results in decorticate spacticity.

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16
Q

Decorticate preparation causes decorticate spasticity due to what phenomenon?

A

“Release phenomenon”, due to tonic excitation of upper areas of the reticular formation no longer under inhibitory cortical influence.

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17
Q

Decorticate spasticity is often seen in humans after stroke, on what side?

A

The hemiplegic side.

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18
Q

This cause of decorticate spasticity is responsible for 60% of intracerebral hemorrhages.

A

Rupture/thrombosis of small arteries of the internal arteries.

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19
Q

This experimental procedure is helpful in the study of reflexes

A

Decerebration

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20
Q

In experimental decerebration, what is lost, what is profoundly altered, and what remains intact?

A

Sensation is lost. Motor control is profoundly altered (b/c descending cortical pathways are interrupted). The brain stem remains intact.

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21
Q

T/F: in decerebration, activity in some descending pathways become hyperactive?

A

True

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22
Q

In decerebration, what reflexes are suppressed, and what reflexes are exaggerated?

A

Flexion reflexes are suppressed, stretch reflexes are exaggerated (selective excitation of gamma motor neurons).

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23
Q

T/F: Humans with brainstem damage signs of decerebration have an optimistic prognosis.

A

False; it’s a poor prognosis in humans.

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24
Q

What happens initially in spinal shock and why?

A

Initially all cord functions (including spinal reflexes) are decreased because of the lack of tonic excitation from higher centers.

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25
Q

T/F: Spinal cord neurons are irreparably damaged after spinal cord transection?

A

False; these neurons gradually regain excitability (days to weeks).

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26
Q

What is the mass reflex and what causes it?

A

The mass reflex happens due to transection of the spinal cord. Evacuation of bladder and colon. Flexor spasm.

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27
Q

T/F: the mass reflex happens as the spinal cord becomes excessively active?

A

True

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28
Q

In spinal shock, what happens to arterial blood pressure and skeletal muscle reflexes integrated in the cord?

A

ABP falls dramatically, skeletal muscle reflexes integrated in cord are blocked.

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29
Q

The pontine reticular nuclei transmit what kind of signals to what musculature, via what spinal tract?

A

Excitatory signals to axial trunk and extensor muscles via the medial reticulospinal tract.

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30
Q

The pontine reticular nuclei receive stimulation from what 2 places?

A

The vestibular and deep cerebellar nuclei.

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31
Q

T/F: the pontine reticular nuclei receive a small degree of natural excitability.

A

False; they recieve a high degree of natural excitability.

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32
Q

The medullary reticular nuclei transmit what kind of signals, to what musculature, via what spinal tract?

A

Inhibitory signals to same musculature as pontine reticular nuclei, via the lateral reticulospinal tract.

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33
Q

The medullary reticular nuclei receive strong stimulus from which 3 areas?

A

The red nucleus, cortex and other motor areas.

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34
Q

T/F: The medullary reticular nuclei only allow for a decrease in tone?

A

False; they allow for both and increase and decrease in tone.

35
Q

T/F: The medullary reticular nuclei counterbalance inhibitory signals from the pontine reticular nuclei.

A

False; they counterbalance excitatory signals from the PRN.

36
Q

On what does the regulatory actions of medullary reticular nuclei on PRN (increasing or decreasing muscle tone) depend?

A

The function needed to be performed.

37
Q

The brainstem is responsible for motor control of which 6 functions?

A 
Movement of eyes
Respiration
Cardiovascular system
GI functions
Equilibrium
Many stereotyped movements
38
Q

What are the 5 descending tracts from brain to SC?

A 
Anterior corticospinal tract
Lateral corticospinal tract
Reticulospinal tracts (medial and lateral often grouped as 1)
Vestibulospinal tract
Rubrospinal tract
Tectospinal tract
39
Q

Which descending spinal tracts are ipsilateral?

A

Vestibulospinal tract
Reticulospinal tracts
Ventral corticospinal tract.

40
Q

Which descending spinal tracts are contralateral?

A

Tectospinal tract
Lateral corticospinal tract
Rubrospinal tract

41
Q

The reticulospinal tract is often considered one, but is actually made up of two tracts. What are they?

A

Pontine (medial) reticular formation

Medullary (lateral) reticular formation.

42
Q

The vestibulospinal tracts originate where and stimulate what?

A

Lateral vestibular nucleus (deiter) to extensor musculature (mainly).

43
Q

The tectospinal tract innervates what musculature in what way? Where does it originate?

A

Innervates cervical musculature in orienting reactions. Originates from the superior colliculus.

44
Q

What tracts make up the lateral motor system of the cord?

A 
Lateral corticospinal tract
Rubrospinal tract (controls more distal muscles of limbs).
45
Q

What tracts make up the medial motor system of the cord and controls what musculature?

A

Vestibulospinal tracts
Tectospinal tracts
Reticulospinal tracts
Anterior corticospinal tracts.

Controls mainly the axial and girdle muscles.

46
Q

T/F: the terms medial and lateral refer to where these tracts lie in the cord?

A

True

47
Q

T/F: the primary motor cortex maintains a vertical and columnar arrangement?

A

True

48
Q

In the primary motor cortex, how many pyramidal cells need to be stimulated to achieve muscle contraction?

A

50-100

49
Q

The dynamic output signals from pyramidal cells are excessively excited when to achieve what?

A

At the onset of muscle contraction to initiate muscle contraction

50
Q

The static output signals from pyramidal cells fire at a fast or slow rate? What do they maintain?

A

Slow. They maintain muscle contraction.

51
Q

What are the 2 phases of voluntary movement?

A

Planning and program phase

Execution phase

52
Q

Signals for movements in the planning and program phase of voluntary movement orginate where and sends information where? Via what?

A

Originate in sensory association cortex, outputs to premotor cortex via basal ganglia and cerebrocerebellum.

53
Q

Signals for movements in the execution phase of voluntary movement are carried from where to where?

A

From premotor cortex, to primary motor cortex, to spinal cord (corticospinal projections).

54
Q

In the execution phase, signals for movements going to the primary motor cortex can also go where?

A

Spinocerebellum.

55
Q

In the execution phase, feedback from the periphery travels where?

A

Spinocerebellum to primary motor cortex.

56
Q

T/F:

It is impossible to separate postural adjustments from voluntary movement?

A

True

57
Q

What are the 2 types of postural reflexes provided to maintain a stable postural background for voluntary movement?

A

Static reflexes (maintain contraction), dynamic short term phasic reflexes (transient movements).

58
Q

T/F:

A major factor of postural control, is with variation in threshold of spinal stretch reflexes.

A

True

59
Q

Variation in threshold of spinal stretch reflexes is caused by changes in ____________of motor neurons and changes in _____________ of gamma efferent neurons to ______________.

A

Excitability. Rate of discharge. Muscle spindles.

60
Q

What are the 3 types of postural reflexes?

A

Vestibular
Tonic
Righting

61
Q

The vestibular apparatus is an organ that detects what?

A

Sensations of equilibrium

62
Q

What are the 3 major components of the vestibular apparatus?

A

Utricle, saccule, semicircular canals.

63
Q

T/F:

The vestibular apparatus provides information about position and movement of the eyes in space

A

False; the head.

64
Q

The vestibular apparatus helps maintain body balance and helps coordinate _______________

A

movement

65
Q

In the utricle and saccule what is the sensory area?

A

The macula.

66
Q

In the utricle and saccule, what kind of sensitivity causes depolarization/hyperpolarization?

A

Directional

67
Q

The utricle and saccule detect orientation of _________ with respect to ___________, and also dectects ____________.

A

Head, gravity. Linear acceleration.

68
Q

The macula of the utricle lies in what plane and plays a large role in determining orientation of the head when a person in in what position?

A

Horizontal plane. Upright.

69
Q

The macula of the saccule lies in what plane? It plays a major role in determining the orientation of the head when a person is in what position?

A

Vertical plane. Lying down.

70
Q

What is the cupula?

A

In the semicircular canals it is a loose, gelatinous tissue mass that lies on top of the crista.

71
Q

When are the semicircular canals stimulated? What are they filled with?

A

When the head begins to rotate. Endolymph.

72
Q

What is the bilateral orientation of the semicircular canals?

A

90 degrees to one another (anterior, horizontal, posterior) each set lying the same plane (right anterior - left posterior. Right and left horizontal. Left anterior - right posterior).

73
Q

As the head begins to rotate, what is the effect on the cupula?

A

Fluid lags behind and bends the cupula.

74
Q

As the cupula bends, what neuronal event takes place?

A

It generates a receptor potential that alters the firing rate in C.N VIII which projects to the vestibular nuclei.

75
Q

The semicircular canals detect what aspect(s) of rotation?

A

Acceleration, deceleration.

76
Q

The semicircular canals are stimulated on which side?

A

The side of rotation (e.g. right head rotation stimulates right semicircular canal).

77
Q

Stimulation of semicircular canals is associated with increased _________________ and ________________

A

Extensor tone. Nystagmus.

78
Q

Why can issues with the semicircular canals cause nystagmus?

A

Because they have connection with the vestibular nuclei of C.N VIII which make connection with cranial nerves of eye movement (III,IV,VI), and the cerebellum.

79
Q

T/F:

The fast component (jump ahead to a new focal spot) is initiated by the semicircular canals?

A

False; fast component stimulated by brain stem nuclei.

80
Q

T/F:

The slow component (tracking) is sometimes initiated by the brain stem nuclei.

A

False; the slow component (tracking) is initiated by the semicircular canals.

81
Q

The semicircular canals is thought to have a predictive function which prevents what?

A

Malequilibrium

82
Q

What are anticipatory correction attributed to?

A

Semicircular canals.

83
Q

The semicircular canals work in close concert with the _____________, especially the _________________

A

Cerebellum. Flocculonodular lobe.

Neurophys II/III (5 decks)

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