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Neurobiology I > Motor Circuits > Flashcards

Motor Circuits Flashcards

1
Q

Muscles come in pairs: when one contracts, the other ____.

A

Stretches

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2
Q

Muscle contraction is (active/passive), whereas muscle stretching is (active/passive). What does “passive” mean in this context?

A

Active

Passive (cannot be directly activated by neurons)

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3
Q

The lower motor neurons are directly involved in receiving information from the ____ ____ and sending information to ____.

A

Spinal cord

Muscles

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4
Q

The upper motor neurons send information from the ___ ___ and the ___ down to ____ motor circuits.

A

Motor cortex
Brainstem
Lower

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5
Q

Upper motor neurons can directly synapse on ___ ___ neurons, but usually synapse on ___ ___ neurons.

A

Lower motor

Local circuit

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6
Q

Where are the local circuit neurons located?

A

Spinal cord

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7
Q

Local circuit neurons synapse on ____ ____ neurons.

A

Lower motor

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8
Q

What are 3 types of sensory information that can be passed to the local circuit neurons? Which one comes directly from the muscles?

A

Proprioceptive (comes directly from muscles)
Pain
Touch

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9
Q

The upper motor neurons are also called the ____ systems.

A

Descending

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10
Q

The ___ ___ and the ____ send information that combines with the descending systems to regulate movement.

A

Basal ganglia

Cerebellum

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11
Q

Each muscle has (one/multiple) neuron(s) that control(s) it.

A

Multiple

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12
Q

Each muscle is made up of multiple ____ ____. Bigger muscles require (more/less/the same) number of these as smaller muscles.

A

Muscle fibers

More

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13
Q

Each motor neuron controls a different set of ___ ____.

A

Muscle fibers

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14
Q

What is a motor neuron pool?

A

All of the neurons that innervate a particular muscle

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15
Q

(Bigger/smaller) muscles and muscles with (low/high) dexterity have more motor neurons.

A

Bigger

High

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16
Q

Motor neurons have their cell bodies in the ___ ___ of the ___ ____.

A

Ventral horn

Spinal cord

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17
Q

Motor neurons synapse in the (ipsilateral/contralateral) spinal cord.

A

Ipsilateral

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18
Q

Muscles’ motor neurons have their cell bodies in (one/multiple) segments in the spinal cord. What type of muscles don’t have their motor neurons’ cell bodies in the spinal cord at all?

A

Multiple

Eye

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19
Q

The cell bodies of the proximal limb muscles (closer to the body) are located (medially/laterally) in the ventral horn to the cell bodies of the distal limb muscles (further away from the body).

A

Medially

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20
Q

What is a motor unit?

A

All of the muscle fibers innervated by the same motor neuron

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21
Q

Each motor neuron innervates (1/ 1 or more) muscle fibers.

A

1 or more

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22
Q

In general, the larger the motor unit, the (smaller/larger) the motor neuron, the (less/more) muscles contract, and the (lesser/greater) the force generated.

A

Larger
More
Greater

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23
Q

In muscle physiology, what is considered to be the smallest unit of force?

A

Motor unit

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24
Q

The greater the motor unit, the (lesser/greater) the force generated.

A

Greater

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25
Q

By definition, a small motor unit MUST:
A) Be in a small muscle
B) Innervate relatively few muscle fibers
C) Generate a relatively small amount of force
D) Have a small motor neuron
E) All of the above

A

B) Innervate relatively few muscle fibers

The other answers aren’t part of the definition for a motor unit

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26
Q

What are the 3 types of motor units?

A

Slow
Fast fatigable
Fast fatigue resistant

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27
Q

Slow motor units:

1) Many or few muscle fibers per motor neuron?
2) Muscle fibers contain many or few mitochondria and blood vessels?
3) Fast or slow to fatigue?
4) What type of muscle movements? Example?
5) High or low threshold of activation?

A

1) Few
2) Many
3) Slow
4) Sustained, low force muscle movements (example- upright posture)
5) Low threshold

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28
Q

Most of the muscles of the lower back fall into which category of motor unit? Why?

A

Slow

They are used for standing and sitting

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29
Q

Which of the 3 categories of motor units has tonic activity?

A

Slow

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30
Q

Fast fatigable motor units:

1) Many or few muscle fibers per motor neuron?
2) Muscle fibers contain many or few mitochondria and blood vessels?
3) Fast or slow to fatigue?
4) What type of muscle movements? Example?
5) High or low threshold of activation?

A

1) Many
2) Few
3) Fast
4) Brief, high force contraction (example- sprinting)
5) High threshold

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31
Q

Fast fatigue resistant motor units:

1) (Low/intermediate/high) level of energy generation and number of muscle fibers per motor neuron?
2) High or low threshold?

A

1) Intermediate

2) High

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32
Q

One muscle can have (one type/ all 3 types) of motor unit(s). If all 3, what would differ between them?

A

All 3

Different percentages of each

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33
Q

What determines the order in which the 3 types of motor circuits are recruited? In which order do they activate?

A

Threshold

Slow -> fast fatigue resistant -> fast fatigable

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34
Q

Tension when referring to muscles is synonymous with what term?

A

Contraction

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35
Q

In general, the amount of force a muscle can use is proportional to its level of ____.

A

Tension/ contraction

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36
Q

How do slow motor units differ from fast fatigue resistant and fast fatigable motor units in terms of force generated and amount of time that maximum contraction can be maintained?

A

Slow motor units: not much force generated, can sustain maximum contraction for a long period of time
Fast fatigue resistant and fast fatigable: more force generated, but maximum contraction cannot be sustained for a long period of time

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37
Q

Muscle tension/contraction is determined by the ___ ___ frequency of the ____ ___ ___.

A

Action potential frequency

Alpha motor neuron

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38
Q

The alpha motor neuron controls what?

A

Motor unit

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39
Q

At a low frequency of action potential firing by an alpha motor neuron, the muscle shows what kind of response? What effect does this yield?

A

Twitching

Yields basic muscle tone

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40
Q

What happens to the level of force a muscle shows after several alpha motor neuron action potentials? Is this due to the level of contraction changing? If not, what is it due to?

A

Force increases
Not due to level of contraction changing
Muscle does not relax in between contractions

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41
Q

Does a single action potential from the alpha motor neuron cause a muscle to contract to its maximum? If not, how is maximum contraction force generated?

A

No- maximum force comes from high rate of action potential firing

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42
Q

When a maximum healthy rate of action potential firing from the alpha motor neuron occurs, what does the graph of time vs force look like?

A

Slight relaxations between action potentials without return to baseline

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43
Q

In smooth fused tetanus, does the muscle relax between alpha motor neuron action potential firings? Is this considered to be a healthy condition? If not, what conditions is this related to?

A

No
No
Charley horse, trigger finger

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44
Q

Larger motor units are usually associated with (smaller/larger) motor neurons.

A

Larger

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45
Q

Larger motor neurons have (less/more) axonal branches.

A

More

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46
Q

Is motor unit size directly or inversely proportional to dexterity? Would a larger motor unit yield high or low levels of dexterity?

A

Inversely proportional

Low

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47
Q

In general, the higher the dexterity of a muscle, the (smaller/larger) the motor units and the (smaller/larger) the motor neurons for each motor unit.

A

Smaller (both)

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48
Q

Compared to a small motor unit, a large motor unit will likely:
A) Be innervated by more neurons
B) Have a larger motor neuron
C) Have more mitochondria per muscle fiber
D) All of the above

A

B) Have a larger motor neuron

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49
Q

Stimulating muscle at low frequency for long period of time:

1) What type of motor units predominated before stimulation? After stimulation?
2) The alpha motor neurons shifted to become more like those that normally control what type of motor units?
3) What principle did this experiment demonstrate?

A

1) Before stimulation: fast fatigable
After stimulation: slow
2) Slow motor units
3) Motor unit plasticity

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50
Q

Athletic training can:
A) Change the firing properties of the motor neuron
B) Change the properties of the muscle fiber
C) Change the size of the muscle
D) All of the above

A

D) All of the above

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51
Q

Training ankle muscle by repeatedly flexing ankle:

1) How did training change the amount of force generated and the amount of time needed to reach maximum force?
2) How did training change the response time and strength of neuronal activity in the muscle?
3) How did training change the action potential firing rate and amplitude of the alpha motor neurons?
4) What principle did this experiment demonstrate?

A

1) Increased amount of force generated
Decreased amount of time needed to reach maximum force
2) Decreased response time
Increased strength of neuronal activity in muscle
3) Increased action potential firing rate
Increased amplitude
4) Motor unit plasticity

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52
Q

Even the simplest reflex needs to integrate information from ____ and ____ neurons.

A

Motor

Proprioceptive

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53
Q

Motor neurons: neurons that activate contraction of ___ ___ or ____ ____.

A

Motor units

Muscle spindles

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54
Q

What are the two types of motor neurons? Which synapses where? Which has a neuromuscular junction?

A

Gamma motor neurons- synapse in spindle fibers

Alpha motor neurons- synapse on muscle fibers, have neuromuscular junctions

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55
Q

Proprioceptive neurons innervate and sense change in the ___ ___ and the ___ ____ ____.

A

Muscle spindle

Golgi tendon organ

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56
Q

What 2 proprioceptive sensory neurons innervate the muscle spindle? Which sensory neuron innvervates the Golgi tendon organ? Which has the bigger and faster neuron(s)?

A

Muscle spindle: Ia and II (biggest and fastest neurons)

Golgi tendon organ: Ib

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57
Q

The proprioceptive sensory neurons Ia, II, and Ib have their cell bodies in the ___ ____ ____.

A

Dorsal root ganglia

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58
Q

Proprioceptive input ascends through and has its synapses in the (contralateral/ipsilateral) (dorsal/ventral) horn.

A

Ipsilateral

Ventral horn

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59
Q

Every muscle has how many spindle(s)? Are spindles located on the inside or outside of muscles? Muscle spindles are innervated by which type of motor neuron and which type of proprioceptive sensory neurons? The effect of the motor neuron on the muscle spindle is (contraction/relaxation).

A 
1 
Inside
Gamma motor neuron
Ia and II
Contraction
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60
Q

The Golgi tendon organ is located at the junction between the ___ and the ___. What type of sensory neuron innervates it?

A

Muscle
Tendon
Ib

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61
Q

The proprioceptive sensory neurons Ia, Ib, and II release what type of neurotransmitter?

A

Glutamate

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62
Q

The Ib sensory neuron with its cell body in the ___ ___ ___ takes information from the ___ ___ ___ to the (ipsilateral/contralateral) ___ ___ and synapses on an ___ ___ that synapses onto the ____ ____ ___, causing muscle (relaxation/contraction).

A 
Dorsal root ganglia
Golgi tendon organ
Ipsilateral
Ventral horn
Inhibitory interneuron
Alpha motor neuron
Relaxation
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63
Q

The Ia sensory neuron with its cell body in the ___ ___ ___ takes information from the ___ ___ to the (ipsilateral/contralateral) ____ ___ and synapses on the ___ ___ ____, causing muscle (relaxation/contraction).

A 
Dorsal root ganglia
Muscle spindle
Ipsilateral
Ventral horn
Alpha motor neuron
Contraction
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64
Q

Both the gamma and alpha motor neurons have their cell bodies in the (ipsilateral/contralateral) ___ ___.

A

Ipsilateral

Ventral horn

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65
Q

The gamma motor neuron with its cell body in the ____ ____ is activated by a(n) (ascending/descending) fiber and carries its information to the ___ ___, causing it to (relax/contract).

A

Ventral horn
Descending
Muscle spindle
Contract

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66
Q

In general, (ascending/descending) controls require fine regulation. Thus, what type of motor neurons give fine motor control?

A

Descending

Gamma motor neurons

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67
Q 
The alpha motor neuron receives input directly from the:
A) Ia sensory afferent
B) Ib sensory afferent
C) Spindle fibers
D) Skeletal muscle
E) More than 1 of the above
A

A) Ia sensory afferent

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68
Q 
The gamma motor neuron synapses on the:
A) Ia sensory afferent
B) Ib sensory afferent
C) Spindle fibers
D) Skeletal muscle
E) None of the above
A

C) Spindle fibers

69
Q

In general, activation of the Golgi tendon organ leads to muscle (relaxation/contraction), whereas activation of the muscle spindle leads to muscle (relaxation/contraction).

A

Relaxation

Contraction

70
Q

The muscle spindle is ____, meaning that it has a thick outer ____ surrounding it.

A

Encapsulated

Membrane

71
Q

The Golgi tendon organ is filled with ____ fibers.

A

Collagen

72
Q

What are considered to be the two most important proprioceptive mechanoreceptor types?

A

Muscle spindle

Golgi tendon organ

73
Q

What type of tactile receptor is also thought to be important for proprioceptive systems? What does it specifically sense?

A

Ruffini

Skin stretch

74
Q

Proprioceptive input is important for 3-D ____ of self and coordination of ____.

A

Perception

Movement

75
Q

Alpha motor neurons have (free/encapsulated) endings and determine muscle _____.

A

Free

Contraction

76
Q

How does the gamma motor neuron regulate the “gain” of the spindle? What does this allow the muscle spindle to sense?

A

Adjusts spindle length

Muscle stretch

77
Q

What part of the muscle gives the most information about the stretch of muscles?

A

Muscle spindle

78
Q

The Ia sensory neurons are most sensitive to the ____ of stretch, which happens when the body is (moving/still), whereas the II sensory neurons are most sensitive to ____ stretch, which happens when the body is (moving/still).

A

Velocity
Moving
Sustained
Still

79
Q

The axons for what sensory function are the fastest conducting?

A

Proprioceptive

80
Q

The monosynaptic stretch reflex is considered to be (voluntary/involuntary) movement. Does a reflex involve higher order (i.e. brain) circuits at all?

A

Involuntary

No

81
Q

Synergistic muscles in the monosynaptic stretch reflex are those that are activated on the (same/opposite) side of the limb.

A

Same

82
Q

Monosynaptic stretch reflex steps:
1) A disturbance such as being jostled on the subway or pouring liquid into a cup being held causes (contraction/stretching) of the muscle
2) Activation of ___ and ____ proprioceptive sensory neurons
3a) Activation of ___ motor neurons on (synergistic/antagonistic) muscles, causing (contraction/relaxation)
AND
3b) Activation of (excitatory/inhibitory) interneurons, causing (inhibition/excitation) of (synergistic/antagonistic) muscles

A

1) Stretching
2) Ia and II
3a) Alpha
Synergistic
Contraction
3b) Inhibitory
Inhibition
Antagonistic

83
Q

On what part of the muscle spindle does the gamma motor neuron synapse?

A

Poles of muscle spindle

84
Q

The muscle spindle goes slack when the muscle ____ or ____ after stretch. Does it go slack while stretching, or only afterward? What happens to the Ia or II sensory neurons’ ability to receive information about the muscle length while the spindle is slack? What re-adjusts the spindle length?

A 
Relaxes
Contracts
Only afterward
Cannot receive information about muscle length while spindle is slack
Gamma motor neuron
85
Q

What happens to the firing of the Ia and II sensory neurons while the muscle is stretched? What would happen to the firing of these sensory neurons after muscle stretch if there were no gamma motor neurons? How does the gamma motor neuron adjusting the spindle length affect these sensory neurons’ firing? What information is carried from the sensory neurons in this case?

A

Muscle is stretched: firing is increased
No gamma motor neurons: firing would cease
Gamma motor neuron’s readjustment enables firing to continue
Changes in length of muscle

86
Q

In general, the more complex the movements, the more active the ___ motor neurons in modulating the ____.

A

Gamma

Spindle

87
Q

The (Ia and II sensory neurons/ gamma motor neurons/ both) are considered to be part of the reflex loop controlling the monosynaptic stretch reflex.

A

Ia and II sensory neurons only

88
Q

The Golgi tendon organ is sensitive to muscle (stretch/contraction/both).

A

Contraction only

89
Q

Contraction of the muscle (shortens/elongates) the Golgi tendon organ and activates the ____ sensory afferent.

A

Elongates

Ib

90
Q

What happens to Golgi tendon organ afferent firing when the muscle is stretched? What happens to the firing when the muscle is contracted?

A

Stretched: firing is slightly above baseline
Contracted: firing is greatly above baseline

91
Q

How many Golgi tendon organs per muscle?

A

1

92
Q

The Golgi tendon organ functions in a (positive/negative) feedback loop to prevent (under-/over-) contraction.

A

Negative

Over-contraction

93
Q

Golgi tendon organ activation part 1:
Muscle (contraction/stretching) activates the ____ sensory neurons of the Golgi tendon organ. These neurons carry their information to the ___ ___ of the ___ ____, where they make ___ synapses. What type(s) of neurons are synapsed upon?

A 
Contraction 
Ib
Dorsal horn
Spinal cord
2
Excitatory interneuron, inhibitory interneuron
94
Q

Golgi tendon organ activation part 2:

1) The inhibitory interneuron synapsed upon by the ___ sensory neuron inhibits the ___ motor neurons attached to (synergistic/antagonistic) muscles, causing (contraction/relaxation).
2) The excitatory interneuron synapsed upon by the ___ sensory neuron excites the ___ motor neurons attached to (synergistic/antagonistic) muscles, causing (contraction/relaxation).

A 
1) Ib sensory neuron
Alpha motor neurons
Synergistic 
Relaxation
2) Ib sensory neuron
Alpha motor neurons
Antagonistic 
Contraction
95
Q

In the Golgi tendon organ activation pathway, descending pathways can act upon which interneuron, for what effect?

A

Inhibitory interneuron

Override GTO signal

96
Q

Strong activity in the Ib sensory afferent will cause the muscle to which it’s attached to (contract/relax).

A

Relax

97
Q

Why is contraction considered active and stretch considered passive?

A

Contraction is caused by a neurological signal, where stretch is not

98
Q

What 3 things can cause a muscle to stretch?

A

Actions of opposing muscles
Being thrown off balance
Weight change of something being held

99
Q

The Ia, Ib, and II sensory neurons all have (ascending/descending/both) pathways.

A

Ascending (only Ib has descending)

100
Q

Active contraction activates what part of the muscle and which sensory neuron(s)? Passive stretch activates what part of the muscle and which sensory neuron(s)?

A

Golgi tendon organ
Ib
Muscle spindle
Ia, II

101
Q

When stepping on a tack, what two sensory systems are activated? Which one does what?

A

Nociceptive- trigger reflex to lift leg that has stepped on tack and shift weight to other leg
Proprioceptive: enable shifting of weight to other leg without falling off balance

102
Q

Stepping on a tack:

1) Nociceptive neurons make synapses in the ____ ___ with ____ that either stay ipsilateral and do what or cross to the contralateral side and do what?
2) The ipsilateral neurons decrease the activity of the (extensor/flexor) muscle and increase the activity of the (extensor/flexor) muscle in the ipsilateral leg.
3) The contralateral neurons increase the activity of the (extensor/flexor) muscle and decrease the activity of the (extensor/flexor) muscle in the contralateral leg.

A 
1) Spinal cord
Interneurons
Ipsilateral: trigger movement of ipsilateral leg
Contralateral: prepare contralateral leg to receive full body weight
2) Extensor
Flexor
3) Extensor
Flexor
103
Q

Toxins such as botox and tetanus toxin (relax/contract/either) muscles through ___ of ___ ___. If applied in the spinal cord, what could be blocked?

A

Either
Inhibition
Vesicle fusion
Reflexes

104
Q

Proprioceptive pathways can ascend (ipsilaterally/contralaterally/either) up to the brain. What does this enable?

A

Either

Coordination of both sides of body

105
Q

Local circuit neurons include what type of neurons and have their cell bodies and axons where?

A

Interneurons

Spinal cord

106
Q

The brainstem controls what type of movements and control of what?

A

Basic movements

Posture

107
Q

The upper motor neurons of the cortex get information from which 2 areas? These areas are responsible for ____ and yielding precise ____ of ____ ____ movement.

A 
Motor cortex
Premotor cortex
Planning 
Control
Complex voluntary
108
Q

The upper motor neurons of the brainstem get information from what 3 areas?

A

Vestibular nucleus
Reticular formation
Superior colliculus

109
Q

The vestibular nucleus of the brainstem gives information about body ____ and ___.

A

Posture

Position

110
Q

The reticular formation of the brainstem, like the vestibular nucleus, gives information about body ___ and ___. Additionally, it coordinates autonomic and somatic ____ motor movements. What is an example of this type of movement?

A

Posture
Position
Stereotyped
Walking

111
Q

The superior colliculus of the brainstem orients movement of the ___ and ___.

A

Head

Eyes

112
Q

The primary motor cortex is (rostral/caudal) to the central sulcus. The premotor cortex is (rostral/caudal) to the primary motor cortex.

A

Rostral (both)

113
Q

Similar to the somatosensory cortex, the motor cortex has a topographical representation of the body called the ___. A disproportionate part of the motor cortex corresponds to the ____ and ____, which require fine motor control.

A

Homunculus
Hands
Mouth

114
Q

Information from the motor cortex descends via 2 major tracts:

1) _____ tract synapses in the ____ ____ to control the ____.
2) _____ tract synapses in the ___ ____ to control the ___ and ___.

A 
1) Corticospinal tract
Spinal cord
Body
2) Corticobulbar tract 
Cranial nerves
Face and mouth
115
Q

The premotor cortex has reciprocal connections with the ___ ___.

A

Motor cortex

116
Q

The premotor cortex can project to ___ circuits in the ___ ___.

A

Local

Spinal cord

117
Q

The premotor cortex is involved in ____ movements. What is an example of this?

A

Conditional

Press lever after bell rings

118
Q

The premotor cortex is important for the _____ and ____ of motor activity as well as _____ of _____ motor tasks, such as ___.

A 
Initiation 
Selection
Coordination 
Complex
Talking
119
Q

The cortical projection neurons are arranged in layers from most superficial near ____ surface to deepest near ____ and ____ ____ ____, which carry axons out.

A

Cortical
Ventricles
White matter tracts

120
Q

The cortical projection neurons of focus have cell bodies in layers ____ and ____ of the cortex and project their axons to the ____ and ____ ____.

A

V
VI
Brainstem
Spinal cord

121
Q

The cortical projection neurons have afferents for many different regions of the brain, including the ____, ____, and _____.

A

Brainstem
Thalamus
Cortex

122
Q

The cortical projection neurons are the (smallest/largest) neurons in the cortex and are (excitatory/inhibitory).

A

Largest

Excitatory

123
Q

Nissl stain identifies what cellular structure and is used to identify what type of projection neurons in the cortex?

A

Ribosomes

Betz cells

124
Q

The Betz cells are the (smallest/largest) projection motor neurons in layer ___ of the cortex and send their axons in some cases all the way down the ____ ____.

A

Largest
V
Spinal cord

125
Q

Upper motor neurons of the cortex that project along the corticobulbar tract will cross to the contralateral side where? These motor neurons control the ___ ___ of the ___.

A

Brainstem
Cranial nerves
Face

126
Q

The upper motor neurons of the cortex that project along the corticospinal tract will cross to the contralateral side where? They descend through the ___ ____ ___ of the ___ ___ and synapse on ___ ____ ____ in the (medial/lateral) ___ ____. These neurons control the (proximal/distal) ____ muscles.

A 
Pyramidal decussation
Lateral white matter  
Spinal cord
Lower motor neurons
Lateral 
Ventral horn
Distal 
Limb
127
Q

The upper motor neurons of the brainstem descend (ipsilaterally/contralaterally) through the ____-____ ____ ___ of the ___ ___. They make _____ synapses on ___ ___ ___ in (ipsilateral/contralateral/both) sides of the (medial/lateral) ___ ____. These neurons control the (proximal/distal) ____ muscles, which control ___ and ____.

A 
Ipsilaterally
Anterior-medial white matter 
Spinal cord
Bilateral 
Lower motor neurons
Both 
Medial
Ventral horn
Proximal
Limb
Posture 
Balance
128
Q

What percent of corticospinal projection neurons cross to the contralateral side? What percent remain ipsilateral?

A

90%

10%

129
Q

In the corticospinal tract, ____% of the axons cross to the contralateral side in the ____ ____ of the ____ and form the (lateral/ventral) corticospinal tract. Neurons in this tract that control the ___ and ____ may synapse directly onto ____ ____ ____, but most synapse onto ___ ____ ___.

A 
90%
Pyramidal decussation 
Medulla
Lateral 
Forearm
Hand
Alpha motor neurons
Local circuit neurons
130
Q

In the corticospinal tract, ____% of the axons remain ipsilateral and form the (lateral/ventral) corticospinal tract. Neurons in this tract synapse (monolaterally/bilaterally) and are important for control of ____ and ____ limb muscles.

A 
10%
Ventral
Bilaterally
Axial 
Proximal
131
Q

Axial limb muscles are directly involved in regulating ____ as well as regulating ____ muscles such as shoulder and hip muscles.

A

Posture

Proximal

132
Q

In the corticobulbar tract, the axons descend (ipsilaterally/contralaterally) and synapse (monolaterally/bilaterally) in what 2 areas of the brain?

A

Ipsilaterally
Bilaterally
Pons, medulla

133
Q

Axons from the corticobulbar tract can synapse on the ___ ___ nucleus (cranial nerve ___) or the ___ ___ nucleus (cranial nerve ___) of the ____, or synapse on the ____ nucleus (cranial nerve ____) of the ____.

A 
Trigeminal motor nucleus 
Cranial nerve V 
Facial motor nucleus 
Cranial nerve VII
Pons
Hypoglossal nucleus
Cranial nerve XII 
Medulla
134
Q

The corticobulbar tract carries information from the (ipsilateral/contralateral) motor cortex (face/body) area.

A

Ipsilateral

Face

135
Q

True or false: the corticospinal tract axons all cross the pyramidal decussation.

A

False

136
Q

A single medial local circuit neuron can innervate (few/many) segments of the spinal cord. Medial local circuit neurons make (ipsilateral/contralateral/both) connections on motor neurons in (medial/lateral) portions of the ventral horn. What kind of muscle function do they control?

A

Many
Both
Medial
Posture

137
Q

A single lateral local circuit neuron can innervate (few/many) segments of the spinal cord. Lateral local circuit neurons make (ipsilateral/contralateral/both) connections on motor neurons in the (medial/lateral) portions of the ventral horn. What kind of muscle function do they control?

A

Few
Ipsilateral
Lateral
Fine control of distal extremities (e.g. arms and fingers)

138
Q

A patient that has difficulty standing upright but can play the piano well is more likely to be having disruption of their (lateral/medial) local circuit neurons.

A

Medial

139
Q

Both the ____ cortex and the ___ cortex can control the facial muscles.

A

Motor cortex

Cingulate cortex

140
Q

Axons from the cingulate motor cortex descend on the (ipsilateral/contralateral/both) side(s). Thus, information from the (ipsilateral/contralateral/both) sides of the cingulate motor cortex can control the contralateral side of the face.

A

Both

Both

141
Q

Damaging the motor cortex or the corticobulbar projections would affect the (upper/lower/both) (ipsilateral/contralateral/both) facial muscles.

A

Lower

Contralateral

142
Q

The facial nerve (cranial nerve VII) is considered to be a(n) (upper/lower) motor neuron.

A

Lower

143
Q

Damaging the facial nerve (cranial nerve VII) or what other area(s) would affect the (upper/lower/both) (ispilateral/contralateral/both) facial muscles.

A

Both sides of cingulate cortex
Both
Contralateral

144
Q

Neurons of the vestibulospinal tract have their cell bodies in the ___ ___ and synapse in one or more parts of the ____ ____. They make (monolateral/bilateral) connections.

A

Vestibular nucleus
Spinal cord
Bilateral

145
Q

The medial vestibular nuclei regulate ____ position by reflex movement of the ___ muscles. They respond to stimulation of the ____-____ ____ of the vestibular system.

A

Head
Neck
Semi-circular canals

146
Q

The lateral vestibular nuclei facilitate activation of the ____ extensor muscles. They respond to activation of the ___ ____ of the vestibular system.

A

Limb

Otolith organs

147
Q

Both the medial and lateral vestibular nuclei maintain ____ in response to disturbances of this.

A

Posture

148
Q

The vestibular nuclei receive information coming from the _____ nerve, or cranial nerve ____.

A

Vestibulocochlear nerve

VIII

149
Q

The reticulospinal tract is involved in (voluntary/involuntary) ____ adjustment. It is made up of (a few/many) (small/large) nuclei.

A

Involuntary
Postural
Many
Small

150
Q

The reticular formation is involved in ____ and ____ control, coordination of ___ movements, regulation of ___ and ____, and temporal and spatial control of ____ and ___ movements for rhythmic motion such as ____.

A 
Cardiovascular 
Respiratory
Eye
Sleep 
Wakefulness
Limb
Trunk
Walking
151
Q

The neurons of the reticulospinal tract primarily synapse on ___ ____ neurons. The reticulospinal tract neurons make (monolateral/bilateral) connections.

A

Local circuit

Bilateral

152
Q

Like the vestibular nuclei, the nuclei of the reticular formation maintain ____ in response to disturbances of this.

A

Posture

153
Q

The reticulospinal tract goes through the ____, ____, and ____, always in approximately the same position in each of these regions.

A

Midbrain
Pons
Medulla

154
Q

The reticular formation nuclei can assigned to what 2 categories according to their function?

A

Modulatory

Premotor

155
Q 
Which of the following tracts synapse bilaterally in the spinal cord? 
A) Corticobulbar
B) Reticulospinal
C) Vestibulospinal 
D) Two of the above
E) All of the above
A

D) Two of the above

Reticulospinal and vestibulospinal; corticobulbar synapses in brainstem

156
Q

Information from the primary motor cortex and premotor cortices, in addition to descending along the corticospinal tract, can be carried to the ____ ____, where it synapses (monolaterally/bilaterally) and is then carried into the (lateral/medial) spinal cord and synapses (monolaterally/bilaterally). This information is used to control ____ adjustments.

A 
Reticular formation
Bilaterally
Medial 
Bilaterally
Postural
157
Q

When a person is told to pull a lever following hearing a bell chime, does the person move their arm first or their leg first? Why?

A

Leg- must adjust posture before pulling lever, or will fall off balance

158
Q

When a person is told to pull a lever following hearing a bell chime, the movement of the arm muscle is considered to be (voluntary/involuntary) and is controlled by neurons of the _____ tract. The movement of the leg muscle is considered to be (voluntary/involuntary) and is controlled by neurons of the _____ tract.

A

Voluntary
Corticospinal tract
Involuntary
Reticulospinal tract

159
Q

True or false: voluntary motor control requires premotor and motor activity, whereas involuntary motor control requires only the motor cortex.

A

False

160
Q

Upper motor neuron syndrome corresponds to damage of the ___ cortex, the ____ cortex, or the _____ tract. Lower motor neuron syndrome corresponds to damage to ____ or ____ motor neurons.

A 
Motor cortex
Premotor cortex
Corticospinal tract
Alpha
Gamma
161
Q

Damage to upper motor neurons would result in muscle (weakness/paralysis/both), whereas damage to lower motor neurons could result in (weakness/paralysis/both).

A

Weakness only

Both

162
Q

Damage to upper motor neurons would result in (mild to no/severe) muscle atrophy, whereas damage to lower motor neurons would result in (mild to no/severe) muscle atrophy.

A

Mild to no

Severe

163
Q

When upper motor neurons are damaged, an initial period of ____ ____ occurs, in which there is (hyperactive/no) movement. This period is followed by (hypoactive/hyperactive) reflexes. What causes the change in reflexes?

A

Spinal shock
No
Hyperactive
Loss of descending input to inhibitory interneurons

164
Q

During the secondary occurrence of hyperactive reflexes following upper motor neuron damage, there is (decreased/increased) muscle tone, fluctuation between ___ and ____ (also called ____), and muscle ____.

A 
Increased
Relaxation 
Contraction 
Clonus
Rigidity
165
Q

While upper motor neuron damage yields (hypoactive/hyperactive) reflexes, lower motor neuron damage yields (hypoactive/hyperactive) reflexes. Why does the change in reflexes occur in lower motor neurons?

A

Hyperactive
Hypoactive
Lower motor neurons (i.e. alpha motor neurons) control reflexes

166
Q

Do the initial signs and symptoms of lower motor neuron damage change as time goes on, or do they persist? In lower motor neuron damage, distribution of symptoms corresponds to site of ____.

A

Persist

Damage

167
Q

Upper motor neuron damage causes loss of (reflexive/voluntary/both) movement, whereas lower motor neuron damage causes loss of (reflexive/voluntary/both) movements.

A

Voluntary

Both

168
Q

What is a normal Babinski response to tickling of foot (i.e. what do the toes do)? In a baby less than 4 months old, tickling the foot causes the toes to do what? Why is this? Would a person with upper or lower motor neuron damage exhibit a Babinski response like that of a young baby?

A

Curl toes down
Toes curl up
Upper and lower motor neurons are not yet connected
Upper motor neuron damage

169
Q

The neurons of the cingulate cortex control the muscles of what area of the face?

A

Forehead

Neurobiology I (18 decks)

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