Question 1

Which of the following best describes the role of acetylcholine (ACh) at the neuromuscular junction?

Accepted Answer

ACh binds to receptors on the sarcolemma, causing the movement of $$\mathrm{Na^+}$$ and $$\mathrm{K^+}$$ across the membrane, leading to depolarization and muscle contraction.

Question 2

A patient presents with exaggerated stretch reflexes. Which of the following is the most likely explanation?

Accepted Answer

Lesions of the corticospinal tract have reduced inhibitory input from the brain to the spinal cord.

Question 3

Which of the following is TRUE regarding the stretch reflex?

Accepted Answer

It is monosynaptic and ipsilateral, causing contraction of the stretched muscle and relaxation of its antagonist.

Question 4

A gymnast maintains balance on a beam by adjusting muscle spindle sensitivity. Which neurons are primarily responsible for this adjustment?

Accepted Answer

Gamma ($$\gamma) $$motor neurons

Question 5

Which of the following best describes the function of central pattern generators (CPGs) at the segmental level of motor control?

Accepted Answer

They are networks of oscillating inhibitory and excitatory neurons that set basic rhythms and patterns of movement.

Question 6

Which of the following is a distinguishing feature of the tendon reflex compared to the stretch reflex?

Accepted Answer

The tendon reflex is polysynaptic and produces muscle relaxation in response to tension.

Question 7

A patient steps on a sharp object with their right foot. Which reflexes are activated to prevent injury and maintain balance?

Accepted Answer

Flexor (withdrawal) reflex in the right leg and crossed-extensor reflex in the left leg.

Question 8

Which of the following is a correct sequence of the five basic components of a reflex arc?

Accepted Answer

Receptor $$\rightarrow$$ Sensory neuron $$\rightarrow$$ Integration center $$\rightarrow$$ Motor neuron $$\rightarrow$$ Effector

Question 9

Damage to which of the following would most likely result in the presence of Babinski's sign in an adult?

Accepted Answer

Corticospinal tract or primary motor cortex

Question 10

Which of the following statements about the plantar reflex is correct?

Accepted Answer

A normal response in adults is downward flexion of the toes when the lateral aspect of the sole is stroked.

Question 11

Which neurotransmitters are released at autonomic motor endings to innervate visceral muscle and glands, and how do they act?

Accepted Answer

Acetylcholine and norepinephrine, acting indirectly via second messengers

Question 12

Which level of the motor control hierarchy is primarily responsible for unconscious planning and fine-tuning of movements before they are executed?

Accepted Answer

Precommand level (cerebellum and basal nuclei)

Question 13

A patient has absent abdominal reflexes. Which of the following is the most likely cause?

Accepted Answer

Lesions in the corticospinal tract

Question 14

Which of the following best explains why visceral motor responses are slower than somatic motor responses?

Accepted Answer

Visceral motor endings use neurotransmitters that act indirectly via second messengers.

Question 15

Which of the following is a real-life example of a learned (acquired) reflex?

Accepted Answer

Diving reflex in experienced swimmers

Question 16

Which of the following best describes reciprocal inhibition during a stretch reflex?

Accepted Answer

Afferent fibers synapse with interneurons that inhibit motor neurons of antagonistic muscles.

Question 17

Which of the following is NOT a function of the precommand level in the hierarchy of motor control?

Accepted Answer

Directly activating lower motor neurons to produce reflexes

Question 18

Which of the following would most likely be observed in a person with chronic diabetes mellitus affecting peripheral nerves?

Accepted Answer

Hypoactive or absent stretch reflexes

Question 19

Which of the following best describes the role of the cerebellum in motor control?

Accepted Answer

Acts on motor pathways through projection areas of the brain stem and on the motor cortex via the thalamus to fine-tune motor activity.

Peripheral Nervous System: Motor Endings, Motor Activity, and Levels of Motor Control

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