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5. Neuro > Motor Control > Flashcards

Motor Control Flashcards

1
Q

What are 2 thing muscles can only do?

A

Contract or relax

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2
Q

How many muscles fibres are activated?

A

All or none

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3
Q

Skeletal muscle is attached to bone by what?

A

A tendon

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4
Q

What are the parts of muscles, from actin and myosin to skeletal muscle?

A 
Actin and myosin myofilaments contained in
Myofibrils, several of these form
Muscle fibres, several of these form
Muscle fasiculis, several of these form
Skeletal muscle
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5
Q

What is a motor unit made up of?

A

An alpha motor neurone (a type of lower motor neurone) and all the extrafusal skeletal muscle fibres it innervates

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6
Q

What does an AP in the alpha motor neurone caise?

A

An AP in all extrafusals

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7
Q

If less extrafusals are being innerated by the alpha motor neurone, what happens to the movement?

A

Greater variation in movement
Increased fine regulation of movement
Eg, fingertips & tongue

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8
Q

Alpha motor neurones controlling distal muscles are found where in the spinal cord?

A

Laterally in spinal cord

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9
Q

Alpha motor neurones controlling proximal muscles are found where in the spinal cord?

A

Medially in spinal cord

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10
Q

What happens when there’s damage to a motor unit?

A

Adjacent motor units get bigger

Decreased co ordination

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11
Q

At a neuromuscular junction, where does the axon divide?

A

Axon divides into a number of short processes that lie in the grooves on the muscle fibre surface

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12
Q

What is the region that lies directly under the terminal portion of the axon called?

A

Motor end plate

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13
Q

What is a neuromuscular junction?

A

The junction of an axon terminal with the motor end plate

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14
Q

What is caused due to the differences in electrochemical gradients across the plasma membrane in a NMJ?

A

Produces a local depolarization of the motor end plate - the end plate potential (EPP)

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15
Q

What is the end plate potential?

A

The NMJ version of excitatory postsynaptic potential (EPSP) but is a much stronger depolarization

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16
Q

What is the magnitude of a single EPP compared to that of an EPSP?

A

End plate potential magnitude is much larger than that of an Excitatory post synaptic potential

17
Q

Why is the magnitue of a simgle EPP larger than that of an EPSP?

A

Because the neurotransmitter is released over a larger surface, therefore binding to more receptors and opening more ion channels

18
Q

Where is the AP then propagated to in one EPP?

A

More than sufficient to depolarize all adjacent fibres in the alpha motor unit
Over surface of the muscle fibre into the T tubules

19
Q

Every AP in a motor neurone normally produces…

A

An AP in each muscle fibre in the motor unit

In contrast to synaptic junctions, where multiple EPSPs must occur in order for threshold to be reached

20
Q

All neuromuscular junctions are….

A

Excitatory

21
Q

What is the definition of muscle tone?

A

It is the degree of contraction of a muscle (or the proportion of motor units that are active ay any one time)

22
Q

A muscle with high tone feels….

A

Firm and rigid

Resists passive stretch

23
Q

A muscle with low tone feels….

A

Soft or flaccid

Offers little resistance to passive stretch

24
Q

When a person becomes increasingly alert, more activation of…. And this causes?

A

Alpha motor neurones

Muscle tone increases

25
Q

What is an upper motor neurone?

A

From motor cortex to spinal cord

26
Q

What is an lower motor neurone?

A

Neurones that connect the impulse from the spinal cord to the effector

27
Q

What are symptoms of upper motor neurone syndromes?

A 
Weakness or paralysis 
Spasticity
Increased muscle tone - hypertonia
Over responsive reflexes - hyperreflexia
Positive babinski sign
28
Q

How to test for the positive babinski sign?

A

Run a sharp instrument along lateral border of sole of foot

Causes extension of big toe (bends up) & fanning of other toes

29
Q

What are symptoms of lower motor neurone syndromes?

A

Weakness or paralysis
Decreased or absent muscle tone (hypotonia)
Decreased or absent refleced (hyporeflexia)
Involuntary muscle twitches (fasciculations)
Muscle atrophy

5. Neuro (16 decks)

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