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 intrafusal muscle fibers?

Accepted Answer

Detecting changes in muscle length for proprioception

Question 3

Which type of motor neuron innervates extrafusal muscle fibers and is responsible for generating movement?

Accepted Answer

Alpha motor neurons

Question 4

A patient has difficulty sensing the position of their limbs in space, but their muscle strength is normal. Which structure is most likely impaired?

Accepted Answer

Intrafusal muscle fibers (muscle spindles)

Question 5

Which of the following statements about motor unit recruitment is TRUE?

Accepted Answer

Small motor units are recruited first to allow for fine control of force

Question 6

The innervation ratio of a muscle refers to:

Accepted Answer

The number of muscle fibers innervated by a single motor neuron

Question 7

Which of the following best explains why eye muscles have a low innervation ratio?

Accepted Answer

They need precise, fine control of movement

Question 8

During an action potential, which event occurs first?

Accepted Answer

Sodium channels open

Question 9

Which of the following is TRUE regarding the relationship between muscle force and velocity?

Accepted Answer

The faster the muscle shortens, the lower the force it produces

Question 10

A person is performing a delicate task, such as threading a needle. Which of the following is most important for this activity?

Accepted Answer

Recruitment of small motor units with low innervation ratios

Question 11

Which of the following best describes the function of gamma motor neurons?

Accepted Answer

They innervate intrafusal muscle fibers to adjust muscle spindle sensitivity

Question 12

If the membrane potential of a neuron does not reach threshold, what is the result?

Accepted Answer

No action potential is generated

Question 13

Which of the following is a characteristic of smaller motor neurons compared to larger motor neurons?

Accepted Answer

They have larger postsynaptic potentials

Question 14

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

Accepted Answer

Muscle properties such as length and velocity affect force output

Question 15

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 16

A muscle is required to produce a rapid, powerful movement. Which of the following motor unit characteristics would be most beneficial?

Accepted Answer

Large motor units with high innervation ratios

Question 17

Which of the following best describes the process of summation in neuronal integration?

Accepted Answer

The additive effect of multiple excitatory and inhibitory postsynaptic potentials to reach threshold

Question 18

If a muscle's motor neuron pool extends across four spinal segments, what does this imply?

Accepted Answer

The muscle receives input from motor neurons located in four adjacent spinal segments

Question 19

Which of the following equations best represents the relationship between membrane potential ($$V_m$$), threshold potential ($$V_{th}$$), and action potential generation?

Accepted Answer

$$V_m = V_{th}$$ \Rightarrow$ action potential is triggered

Question 20

A person is unable to generate sufficient force during a muscle contraction, even though all motor units are recruited. Which of the following is the most likely explanation?

Accepted Answer

The muscle is shortening too quickly, reducing force output

Control of Muscle: Motor Units, Neuron Pools, and Muscle Fibre Types

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