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EXCI360 > Lecture 7: Motor System II > Flashcards

Lecture 7: Motor System II Flashcards

1
Q

Motor (pyramidal) pathway is composed of:

A

2 order neurons

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2
Q

Motor (pyramidal) pathway is composed of 2 order neurons:

A

-1st order neuron: upper motor neuron
-2nd order neuron: lower motor neuron

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3
Q

1st order neuron (of the motor pathway) : upper motor neuron starts at __ and ends at

A

Starts at the MOTOR CORTEX and ends at the VENTRAL (ANTERIOR) HORN of the spinal cord

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4
Q

1st order neuron: upper motor neuron: stimulates and modulates:

A

The activity of the lower motor neuron

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5
Q

Motor pathway: 1st order neuron have the __ fibers of the CNS

A

Longest fibers of the CNS!

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6
Q

2nd order neuron of the motor neurons: Lower motor neuron starts at __ and ends at __

A

Starts at the anterior horn of the spinal cord and ends at the neuromuscular
junction.

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7
Q

2nd order neuron of the motor patway: lower motor neuron: exits _

A

muscles

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8
Q

2nd order neuron of the motor pathway: Lower motor neuron is integrated in __

A

The circuit of motor reflexes

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9
Q

Motor cortex is located in:

A

Frontal lobe

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10
Q

Motor cortex is located in the frontal lobe and divided into

A

3 sub areas

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11
Q

Motor cortex is located in the frontal lobe and divided into 3 sub areas:

A
  • Primary motor cortex
  • Premotor area
  • Supplemental motor area
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12
Q

Motor association cortex is composed of (2):

A

(1) Premotor area
(2) Supplemental motor area

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13
Q

Primary motor cortex:
Located in the

A

Precentral gyrus (frontal lobe)

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14
Q

Primary motor cortex:

A

Map of a motor representation of body muscles.

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15
Q

Primary motor cortex has unequal:

A

Topographic representation

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16
Q

Primary motor cortex: Penfield’s homunculus:

A

small muscles with low innervation ratio have greatest representation (e.g. fingers, hand, face)

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17
Q

Primary motor cortex: Stimulation of specific primary motor area (e.g. Legs) leads to:

A

Contraction of
muscles of the associated region of the body (i.e. Legs).

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18
Q

Map of the body representation in the cortex: output: motor cortex

A

Left hemisphere section controls the body’s right side

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19
Q

Map of the body representation in the cortex: Input: sensory cortex:

A

Left hemisphere section receives input from the body’s right side

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20
Q

Organization of the Primary Motor Cortex has __ horizontal layers

A

6

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21
Q

Layer 5 of the primary motor cortex (2) :

A

(1) House of the UPPER MOTOR NEURONS (giant pyramidal neurons=Betz cells)

(2) DESCENDING OUTPUT layer (i.e. gives rise to descending pyramidal tracts.

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22
Q

Betz cells

A

Giant pyramidal neurons

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23
Q

Primary motor cortex: Layers 2-4:

A

INPUT LAYERS from other
cortical areas (e.g. motor association
cortex, somatosensory cortex…)

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24
Q

Primary motor cortex: layer 6:

A

CORTICAL OUTPUT layer gives
rise to cortico-cortical fibers

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25
Q

Organization of the primary cortex is in __ and __

A

6 Horizontal layers and vertical columns

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26
Q

Primary motor cortex: Vertical columns: structure

A

< 1 mm in diameter, high density of neurons (thousands each).

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27
Q

Primary motor cortex: vertical columns function as:

A

Functional unit : each column stimulates a single muscle or a group of synergistic muscles (motor units)

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28
Q

Premotor area: organization

A

Topographical organization similar to
primary motor cortex.

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29
Q

Premotor area: integrative processing system:

A

Uses information from input (sensory, visual…) to determine output (motor) response

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30
Q

premotor area functions as

A

an integrative processing system

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31
Q

Premotor area: function

A

planning movement

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32
Q

Activation of the premotor area results in

A

more complex patterns of movement (e.g.
position the shoulders and arm so that the
hands are properly oriented to perform
specific tasks).

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33
Q

premotor area works in concert with:

A

other motor areas
(primary motor, basal ganglia, thalamus,
cerebellum …).

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34
Q

Supplemental motor area (SMA): specific _

A

topographical organization

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35
Q

Supplemental motor area (SMA): often elicits:

A

BILATERAL movements (e.g., grasping of both hands).

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36
Q

Supplemental motor area (SMA): functions:

A

in concert with premotor area for control of POSTURE and
position (e.g., positional movements of the head and eyes).

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37
Q

Motor cortex-Specialized Areas: Broca’s area: Dedicated to:

A

Motor speech production (i.e.
word formulation)

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38
Q

Broca’ s area: located in:

A

the dominant hemisphere (i.e. left
hemisphere for a right-handed person).

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39
Q

Broca’s area: Damage causes

A

Language production deficits
(inability to form words): Broca’s (or motor) aphasia.

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40
Q

Broca’s (or motor)
aphasia.

A

language production deficits
(inability to form words)

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41
Q

Motor cortex: 3 specialized areas:

A

(1) Broca’s area

(2) Hand skills area

(3) Eye movement and head rotation areas

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42
Q

Motor Cortex-Specialized Areas: Hand skills area are for performing:

A

Coordinated and Purposeful hand movements.

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43
Q

Motor cortex: hand skills: damage causes:

A

motor apraxia:
the inability to perform coordinated
hand movements

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44
Q

Motor apraxia:

A

The inability to perform coordinated
hand movements

45
Q

Motor Cortex- Specialized Areas: eye movement and head rotation areas purpose (2):

A

(1) For coordinated voluntary head and eye movements towards specific objects.
(2) Modulate the vestibulo-ocular reflex.

46
Q

Explain pyramidal cortico-spinal pathway

A

Slide 11-12

47
Q

Explain cortico bulbar pathway

A

Slide 13

48
Q

The activity of upper MNs in the cortex controls:

A

movement, rather than individual muscles
contraction (i.e. coordination function)

49
Q

The UMN (upper motor neurons) have an:

A

INHIBITORY control on the MOTOR REFLEXES

50
Q

Stimulation of the motor cortex (i.e. upper MNs) initiatesL

A

the excitation of several muscles and simultaneous
suppression of others.

51
Q

A particular movement (e.g. hand movement) can be
elicited by stimulation of

A

widely separated cortical sites.

52
Q

Regions responsible for initiating different movement:

A

Overlap substantially

53
Q

The force generated by contracting muscles (i.e.
magnitude) depends on:

A

The firing rate of upper MNs.

54
Q

The direction of the force produced by muscles depends on:

A

The activity the upper MNs.

55
Q

Extrapyramidal pathways: Signals are relayed through multiple accessory pathways involving

A

basal ganglia, cerebellum, brainstem nuclei. Most of these pathways
modulate movement through the pyramidal pathway (UMN & LMN).

56
Q

Extrapyramidal pathways =

A

Accessory (indirect pathways)

57
Q

Extrapyramidal pathways (4) :

A

(1) BASAL GANGLIA PATHWAYS
(2) CEREBELLUM PATHWAYS
(3)VESTIBULOSPINAL TRACTS PATHWAY
(4) CORTICOVORUBROSPINAL PATHWAY

58
Q

Basal ganglia pathways:

A

Complex motor actions

59
Q

Cerebellum pathways:

A

Movement Coordination

60
Q

Vestibulospinal tracts pathway:

A

Antigravity and equilibrium

61
Q

Corticorubrospinal pathway:

A

fine motor control

62
Q

The Cortico-Rubro-Spinal pathway serves as

A

an
alternative pathway to transmit cortical motor
signals to the spinal cord (Accessory route).

63
Q

Cortico Rubro spinal pathway:

A

motor cortex -> red nucleus -> spinal cord

64
Q

Stimulation of red nucleus causes

A

motor
movement in specific groups of muscles but not as
precise as primary motor cortex.

65
Q

Input from primary motor cortex to the red nucleus
(midbrain):

A

Corticorubral tracts.

66
Q

Cortico-rubro-spinal pathway:Primary motor cortex fibers synapse in:

A

the lower
portion of the red nucleus called the magnocellular
portion.

67
Q

Cortico-rubro-spinal tract: magnocellular portion fibers give rise to:

A

Rubrospinal tract

68
Q

Rubrospinal tract:

A

(1) Decussates in lower Medulla
(2) Descends adjacent and anterior to the pyramidal tract
(3) Terminates mostly on interneurons but also on motor
neurons (LMNs).

69
Q

Abnormality in the stretch reflexes response suggests that there may be
damage to

A

the lower motor neuron or upper motor neuron

70
Q

Hyporeflexia

A

weak (or absent) reflex response:

71
Q

Hyporeflexia: the problem is in the:

A

lower motor neuron

72
Q

hyporoflexia: disruption of either:

A

afferent or efferent fibers (PNS) in the stretch reflex loop (e.g.,
cut in the fibers, neuropathies, nerve or root compression…).

73
Q

Hyporeflexia: localisation of a spinal segment:

A

(1) Pastellar reflex corresponds to L4
(2) Biceps reflex corresponds to C5-C6

74
Q

Hyperreflexia:

A

strong reflex response:

75
Q

Hyperreflexia: the problem is in:

A

the upper motor neuron

76
Q

The distribution of facial weakness provides:

A

Important
localizing clues indicating whether the underlying injury
involves the upper motor neuron (UMN) or the lower
motor neuron (LMN)

77
Q

Injury to the primary motor cortex (lesion A) causes

A

a weakness of the contralateral inferior facial muscles

78
Q

Injury to the primary motor cortex (lesion A) causes a
weakness of the contralateral inferior facial muscles (2) :

A

(1) Input to inferior facial muscles from the UMN in
the primary motor cortex is lost.
(2) Input to superior facial muscles from the UNM
in the premotor areas (cingulate gyrus) remains
intact because this input projects bilaterally.

79
Q

Injury to corticobulbar tract (lesion B) causes a weakness of:

A

the contralateral inferior facial muscles:

80
Q

Injury to corticobulbar tract (lesion B) causes a
weakness of the contralateral inferior facial muscles:

A

(1) Input to inferior facial muscles from the UMN in primary
motor cortex is lost.
(2) Input to superior facial muscles from the UNM in the
premotor areas (cingulate gyrus) remains intact because
this input projects bilaterally

81
Q

Injury to the facial motor nucleus or its nerve (lesion C) causes:

A

a weakness of all muscles of facial
expression on the same side of the lesion

82
Q

Injury to the facial motor nucleus or its nerve (lesion
C) causes a weakness of all muscles of facial
expression on the same side of the lesion:

A

input to superior and inferior facial muscles from LMN
is lost.

83
Q

Aphasia:

A

disorder in the comprehension and/or expression of speech

84
Q

Broca’s (motor) aphasia:

A

loss of the ability to produce speech

85
Q

Wernicke’s (non-motor) aphasia (fluent aphasia):

A

not coherent speech

86
Q

Broca’s aphasia: Characterized by:

A

the loss of the ability to
produce speech (i.e. inability to form words)

87
Q

Lesion in the Broca’s area:

A

The posterior inferior
frontal gyrus (inferior part of the motor cortex).
For that is also called motor aphasia.

88
Q

Broca’s aphasia: mostly caused by:

A

a stroke

89
Q

Broca’s aphasia: varies from:

A

the complete loss of the ability to
speak to struggle to speak (non-fluent speech).

90
Q

Broca’s aphasia: possibility of:

A

recovery by speech therapy

91
Q

Myasthenia gravis:

A

a NEUROMUSCULAR DISEASE that causes weakness in the
muscles (e.g. drooping of eyelids, difficulty
swallowing, shortness of breath)

92
Q

Myasthenia gravis: pathology at:

A

the neuromuscular junction

93
Q

Myasthenia gravis: acetylcohline receptors on the muscle cell membrane are:

A

-BLOCKED (or DESTROYED) by
antibodies (autoimmune disease),

  • REDUCED transmission of Ach in the muscle
  • IMPAIRED MUSCLE CONTRACTION
94
Q

Myasthenia gravis treatment:

A

CHOLINESTERASE INHIBITORS: inhibit
the metabolism of Ach by the cholinesterase
enzyme (i.e., keep more Ach in the synaptic
cleft), Thus, boost signals between nerves and
muscles to improve muscle strength

95
Q

Upper motor neuron lesion: site of the lesion:

A

Cortex
Brainstem
Spinal cord

96
Q

Upper motor neuron lesions: muscle weakness:

A

Yes (plegia)

97
Q

Upper motor neuron lesion: muscle tone:

A

increased (spasticity)

98
Q

upper motor neuron lesion: muscle atrophy:

A

disuse atrophy

99
Q

Upper motor neuron lesion:fasciculation (muscle twitching)

A

No fasciculations

100
Q

Upper motor neuron lesion: Tendon / stretch reflex:

A

hyperreflexia (strong reflex)

101
Q

Upper motor neuron lesions: Babinski sign (plantar reflex):

A

positive babinski sign

102
Q

Lower motor neuron lesion: site of the lesion:

A

Anterior horn
Roots
Nerves
Neuromuscular junction

103
Q

Lower motor neuron lesion: muscle weakness:

A

Yes (myopathy)

104
Q

Lower motor neuron lesion: muscle tone:

A

Decreased (hypotonia)

105
Q

Lower motor neuron lesion: muscle atrophy:

A

Denervation atrophy

106
Q

Lower motor neuron lesion: fasciculation (muscle twitching):

A

Fasciculations

107
Q

Lower motor neuron lesion: tendon / stretch reflex:

A

hyporeflexia (weak reflex)

108
Q

lower motor neuron lesion: babinski sign (plantar reflex):

A

Negative babinski sign

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