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Neurophysiology Loyola > Postural Stability, Orientation, Praxis > Flashcards

Postural Stability, Orientation, Praxis Flashcards

1
Q

Define postural stability

A

Maintaining position

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2
Q

Define orienting movements

A

Movements that turn the body toward a sensory stimulus

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3
Q

Define voluntary actions AKA praxis

A

Includes speech, facial expressions, reaching, grabbing, holding, playing

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4
Q

Medial tracts function in
A) Orientation
B) Praxis
C) Posture

A

A and C (orientation and posture)

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5
Q

Lateral tracts function in
A) Orientation
B) Praxis
C) Posture

A

B (Praxis)

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6
Q

The lateral vestibulospinal tract, reticulospinal tract, and anterior corticospinal tract function in what?

A

They are parts of the medial tract that function in posture

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7
Q

The medial vestibulospinal tract and tectospinal tract function in what?

A

They are parts of the medial tract that function in orientation

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8
Q

The lateral corticospinal tract, corticobulbar spinal tract, and rubrospinal tract function in what?

A

They are parts of the lateral tracts that function in praxis

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9
Q

Which tracts function in complex movements?

A

Corticospinal and corticobulbar tracts

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10
Q

Complex movements require __________ projections while simple movements require ____________ projections

A

Direct; indirect

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11
Q

What are the direct projections involved in complex movements?

A

From motor control centers to motoneurons

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12
Q

What are the indirect projections involved in simple movements

A

From motor control centers through motor interneurons to motoneurons

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13
Q

Which tracts are involved with simple movements?

A

All descending tracts

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14
Q

What is the affect of a motoneuron lesion on volitional movement

A

Weak or none

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15
Q

What is the affect of a motoneuron lesion on reflexive movement

A

hyporeflexia or areflexia

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16
Q

What is the affect of a motoneuron lesion on muscle tone

A

Decreased or absent

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17
Q

What is the affect of a motoneuron lesion on muscle appearance

A

Moderate to severe atrophy from disuse

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18
Q

What is the affect of a motoneuron lesion on EMG findings suggestive of muscle denervation

A

Fibrillations, fasciculations

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19
Q

What is the effect of a lesion of descending tracts (corticospinal included) on volitional movement

A

None: paralyzed (if corticospinal tract is involved)

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20
Q

What is the effect of a lesion of descending tracts (corticospinal included) on reflexive movement

A

Hyper-reflexia

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21
Q

What is the effect of a lesion of descending tracts (corticospinal included) on muscle appearance

A

Mild atrophy from disuse mitigated by the hyper-reflexive use

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22
Q

What is the effect of a lesion of descending tracts (corticospinal included) on EMG findings suggestive of muscle denervation

A

Typically transient if present

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23
Q

Medial tracts correspond with ____________ and _________

A

posture and orientation

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24
Q

Lateral tracts correspond with _______

A

Praxis

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25
Q

Motoneuron death results in ___________

A

no movement, hypo/areflexia, atrophy

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26
Q

Motor tract lesions result in _______________

A

no volitional movements, hyperreflexia, no atrophy

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27
Q

Difficulty of holding a posture depends on what 2 things?

A

Center of mass and support surface

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28
Q

What is a “support surface”

A

Point at which the body touches the ground

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29
Q

Which of the following positions is easiest and why?
A) Lying prone
B) Sitting
C) Bipedal upright

A

A) lying prone because it has the maximum support surface

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30
Q

Which of the following positions is most difficult and why?
A) Lying prone
B) Sitting
C) Bipedal upright

A

C) Bipedal upright because there is limited support surface

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31
Q

Center of force must lie over ______________

A

support surface

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32
Q

What is the force equation?

A

Mass x acceleration = force

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33
Q

Feed forward reflexes are engaged in ______________

A

standing

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34
Q

Postural adjustments only occur when there is perturbation or a disturbance of equilibrium - true or false?

A

FALSE: Postural adjustments occur in the absence of any actual perturbation, precluding any disturbance of equilibrium before it happens

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35
Q

Somatosensory afferents detect and signal unexpected forces that impact the COM and elicit feedback corrections from _______________

A

Descending postural motor tracts

36
Q

Give the pathway for the descending postural tract

A

Feedforward adjustments –> descending postural tract –> motor interneurons

37
Q

LVST and RST terminate on _____________

A

Gamma motoneurons–> gamma loops –> alpha motoneurons

38
Q

Which motoneuron elicits a contraction?

A

Alpha-motoneurons

39
Q

How do descending postural tracts play a role in feedback?

A

By modifying corrective reflexes

40
Q

Reversal of ___ reflex from inhibition to excitation happens in the feedback by descending postural tracts

A

lb

41
Q

Increased sensitivity of ___ reflex during equilibrium instability happens in feedback by descending postural tracts

A

la

42
Q

What are the postural descending tracts?

A

Lateral vestibulospinal tract (LVST), reticulospinal tract (RST), and anterior corticospinal tract (ACST)

43
Q

What input does the superior colliculus receive?

A

Primarily visual, but also auditory and somatosensory

44
Q

Define sensory-motor transformation

A

Transformation of sensory input by the superior colliculus into a motor map

45
Q

Give the pathway for orienting movements

A

Sensory information –> superior colliculus –> tectospinal tract –> interneurons and central pattern generators in the brainstem and cervical spinal cord –> orienting movement of shoulders, neck, and eyes toward a stimulus on the opposite side

46
Q

Define praxis

A

Physical actions that arise from cognitive processes, including internal thoughts and perceptions of external events

47
Q

What is the function of the rubrospinal tract in praxis?

A

Fundamental gross movements

48
Q

What is the function of the lateral corticospinal tract in praxis?

A

Volitional movements of skeletal muscles in the neck, body, and limbs

49
Q

What is the function of the corticobulbar tract in praxis?

A

Volitional movement of the skeletal muscles in the oral cavity, larynx, and face

50
Q

What is the origin of the rubrospinal tract?

A

Red nucleus

51
Q

Where does the rubrospinal tract cross?

A

At the midline at the level of the red nucleus

52
Q

What does the rubrospinal tract end in?

A

Spinal cord ventrolateral to the sorticospinal tract

53
Q

What does the rubrospinal tract support?

A

Posture, locomotion, and reaching

54
Q

Give the pathway of fine voluntary movements

A

Cortex (primary motor, somatosensory areas of parietal, premotor, and supplementary motor) –> corticospinal and corticobulbar tracts –> interneurons and motoneurons in the spinal cord and cranial nerve nuclei

55
Q

Define somatotopy

A

Relative cortical area controlling different body parts related to the precision with which movements of the regulated muscles are controlled

56
Q

Give the detailed pathway of fine voluntary movements

A

Cortex –> corticospinal and corticobulbar tracts –> internal capsule –> cerebral peduncle –> pons-pontine nuclei –> medulla-pyramid –> spinomedullary junction

57
Q

Voluntary control of muscles on one side of the body depends on neurons in the motor cortex on which side?

A

Contralateral (opposite)

58
Q

What is the function of the corticobulbar tract at the termination site of the motor trigeminal nucleus?

A

Muscles for chewing

59
Q

What is the function of the corticobulbar tract at the termination site of facial nucleus

A

Muscles of facial expression

60
Q

What is the function of the corticobulbar tract at the termination site of nucleus ambiguous

A

Laryngeal and upper airway muscles

61
Q

What is the function of the corticobulbar tract at the termination site of the spinal accessory nucleus (spinal cord)

A

Muscles used for shrugging the shoulders and turning the head

62
Q

What is the function of the corticobulbar tract at the termination site of the hypoglossal nucleus

A

Control tongue muscles

63
Q

What are clinical signs of a unilateral dysfunction of the corticobulbar tract at the termination site of the motor trigeminal nucleus?

A

No discernible deficit, chewing muscles receive bilateral inputs

64
Q

What are clinical signs of a unilateral dysfunction of the corticobulbar tract at the termination site of the facial nucleus

A

Loss of expressions in the contralateral lower face

65
Q

What are clinical signs of a unilateral dysfunction of the corticobulbar tract at the termination site of the nucleus ambiguous

A

Deficits in swallowing or articulation

66
Q

What are clinical signs of a unilateral dysfunction of the corticobulbar tract at the termination site of the spinal accessory nucleus (Spinal cord)

A

Weakness in shrugging the ipsilateral shoulder and rotating the head to look contralaterally

67
Q

What are clinical signs of a unilateral dysfunction of the corticobulbar tract at the termination site of the hypoglossal nucleus

A

Contralateral loss, tongue sticks out toward the side fo the lesion

68
Q

Corticobulbar tract ALWAYS controls motoneurons and movements contralateral to the side of origin - true or false?

A

FALSE; it does not always do this

69
Q

Fine control of muscles in the bottom half of the face are important for which activities?

A

Eating and speech

70
Q

Does the corticobulbar tract directly or indirectly innervate the motoneurons that control muscles of facial expression?

A

Directly

71
Q

Is the top half of the human face primarily under direct or indirect motor control?

A

Indirect

72
Q

Is corticobulbar tract innervation of facial motoneurons controlling the upper face muscles mostly unilateral or bilateral?

A

Bilateral

73
Q

What is the advantage of direct projections of the corticobulbar tract from motor control centers to motoneurons?

A

Support of the ability to deliberately make fine movements

74
Q

What is the advantage of indirect projections of the corticobulbar tract from motor control centers to motoneurons?

A

Support of simple bilateral movements; may support fine movements but requires practice to successfully engage this

75
Q

Which is easier, fine control of the bottom half of the face or the top half?

A

Bottom half

76
Q

Control of the top half of the face is dictated by what part of the brain?

A

Anterior cingulate gyrus

77
Q

Control of the bottom half of the face is by what part of the brain?

A

Primary motor cortex

78
Q

What is the outcome of a facial motoneuron lesion?

A

Cannot move the face on the side of the lesion

79
Q

What is the outcome of a supranuclear (above the facial nucleus) lesion

A

Impacts the bottom half of the contralateral face musculature; can’t lift mouth on the side of the lesion to smile; can frown bilaterally

80
Q

What is the effect on emotionally motivated movements by a corticobulbar lesion?

A

Can’t make facial expressions voluntarily, but CAN make reactions emotionally

81
Q

What part of the brain controls volitional movement of the brain (mostly the contralateral bottom half)

A

Primary motor and premotor cortices

82
Q

What is amimia

A

The ability to make voluntary facial expressions in response to a command, but not in association with an emotion

83
Q

What part of the limbic system control emotional facial expressions of the top half of the face?

A

Anterior cingulate gyrus

84
Q

Which part of the cortex is involved in communication being a reason for action (i.e., people reacting to verbal requests)?

A

Primary motor cortex

85
Q

Which part of the cortex is involved in internal reasons for action (i.e., internal thoughts, emotions, motivations)

A

Supplementary motor area

86
Q

Which part of the motor cortex is involved in external reasons for action (i.e., reactions to objects or stimuli in the environment)?

A

Premotor cortex

Neurophysiology Loyola (7 decks)

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