Question 1

Which of the following best describes a motor unit?

Accepted Answer

A motor neuron and all the extrafusal muscle fibers it innervates

Question 2

What is the primary function of gamma ($$ \gamma ) $$motor neurons?

Accepted Answer

To control the sensitivity of muscle spindles

Question 3

Which of the following statements about the innervation ratio is correct?

Accepted Answer

A low innervation ratio allows for precise, fine motor control

Question 4

During muscle contraction, which of the following occurs first?

Accepted Answer

Summation of excitatory postsynaptic potentials (EPSPs) to reach threshold

Question 5

Which type of muscle fiber is primarily responsible for sensing changes in muscle length?

Accepted Answer

Intrafusal muscle fibers

Question 6

A patient has difficulty performing fine motor tasks, such as threading a needle. Which of the following is most likely true about the affected muscles?

Accepted Answer

They have a low innervation ratio

Question 7

Which of the following best explains why larger motor units produce more force than smaller ones?

Accepted Answer

They innervate more muscle fibers

Question 8

What is the role of the motor neuron pool?

Accepted Answer

It is the collection of all motor neurons innervating a single muscle

Question 9

If the membrane potential of a neuron is at $$ -70 \ \mathrm{mV} $$ and an excitatory postsynaptic potential (EPSP) depolarizes it by $$ +15 \ \mathrm{mV} $$, what is the new membrane potential?

Accepted Answer

$$-55 \ \mathrm{mV}$$

Question 10

Which of the following is TRUE regarding the recruitment of motor units during a voluntary muscle contraction?

Accepted Answer

Small motor units are recruited first, followed by larger ones as force increases

Question 11

A person is performing a rapid, high-force movement. Which of the following is most likely to occur in the motor units involved?

Accepted Answer

Both small and large motor units are recruited to generate sufficient force

Question 12

Which of the following best describes the function of extrafusal muscle fibers?

Accepted Answer

They generate the force required for movement

Question 13

Which of the following scenarios best illustrates the concept of neuronal integration?

Accepted Answer

Multiple excitatory and inhibitory inputs summing to determine if a neuron fires an action potential

Question 14

If a muscle is required to maintain the same force output at two different lengths, which of the following must the nervous system account for?

Accepted Answer

The force-length relationship of the muscle

Question 15

Which of the following is a direct result of the opening of Na$$ ^+ $$ channels in the neuronal membrane?

Accepted Answer

Depolarization leading to an action potential

Question 16

A muscle spindle is primarily composed of which type of muscle fiber?

Accepted Answer

Intrafusal fibers

Question 17

Which of the following best explains why the same neural activation does not always produce the same force output in a muscle?

Accepted Answer

Muscle properties such as length and velocity affect force production

Question 18

Which of the following is TRUE about the distribution of muscle fibers within a single motor unit?

Accepted Answer

They are distributed throughout the muscle and mixed with fibers from other motor units

Question 19

Which of the following best describes the relationship between the size of a motor neuron and its conduction velocity?

Accepted Answer

Larger motor neurons have faster conduction velocities due to greater axon diameter

Question 20

A person is unable to sense the position of their limb in space after a nerve injury. Which structure is most likely damaged?

Accepted Answer

Intrafusal muscle fibers (muscle spindles)

Control of Muscle: Motor Units, Neurons, and Muscle Fibres in Motor Control

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