Question 1

Which is TRUE about the function of the cerebellum?

Accepted Answer

The cerebellum is involved in coordinating body movements, maintaining posture, and receiving input from sensory pathways. Additionally, it stores the memory of motor movements that involve several joints. Therefore, all of the choices are correct about its function.

Question 2

Practicing a movement allows for "fine-tuning" the original program so that the movement can be executed with fewer corrections.

Accepted Answer

Practicing a movement helps in refining and improving the motor program associated with it, which ultimately leads to executing the movement more accurately with fewer corrections.

Question 3

You are a surgeon who is implanting a medical device in the brain of a patient with a persistent tremor in his right hand that obstructs his ability to write.Where do you implant the device that has been shown to dampen these tremors?

Accepted Answer

The tremors in the patient's right hand indicate a problem with the motor function on the right side of the body. Thus, the device should be implanted in the left corticospinal pathway or sensorimotor cortex, as they control movements on the opposite (right) side of the body. The other options are not directly related to controlling motor function on the opposite side of the body.

Question 4

Which best describes the specific cause of Parkinson's disease?

Accepted Answer

Parkinson's disease is caused by the gradual deterioration of neurons in the substantia nigra, which are responsible for producing dopamine. The reduction in dopamine release leads to the characteristic symptoms of the disease, such as tremors, rigidity, and bradykinesia.

Question 5

Afferent information about body movement is in part integrated at the level of the interneurons controlling the firing of alpha motor neurons.

Accepted Answer

Afferent information about body movement is integrated at the level of the interneurons, which in turn control the firing of alpha motor neurons. This process is essential for the regulation of muscle tone and the coordination of movements.

Question 6

Which of the following is NOT true of corticospinal fibers?

Accepted Answer

Corticospinal fibers are not collectively referred to as the extrapyramidal system. The extrapyramidal system consists of other motor pathways that originate in the basal ganglia and other subcortical structures, but not in the cortex. Corticospinal fibers are part of the pyramidal system, which consists of motor pathways that originate in the cerebral cortex and descend through the medulla oblongata. Choices A, B, C, and E are true statements about corticospinal fibers.

Question 7

When a walking person lifts one foot off of the ground,which of these happens?

Accepted Answer

When a person lifts one foot off the ground, the body leans so that the center of gravity shifts over the foot that is on the ground. This is necessary to maintain balance and prevent falling over. The body essentially creates a new base of support with the foot that is still on the ground, and the center of gravity shifts over this foot to maintain stability.

Question 8

During motor activity,alpha-gamma coactivation provides important information regarding muscle length to the higher motor control centers.

Accepted Answer

Alpha-gamma coactivation involves the simultaneous activation of alpha motor neurons (which control the extrafusal fibers of a muscle) and gamma motor neurons (which control the intrafusal fibers of a muscle). This coactivation allows for accurate control of muscle length during motor activity and provides important feedback to the higher motor control centers about the state of the muscles.

Question 9

What is the definition of "muscle tone"?

Accepted Answer

Muscle tone refers to the resistance of a muscle to continuous passive stretch. It is the result of the involuntary low-level contraction of muscle fibers, even when the muscle is at rest.

Answer: D
 Muscle tone is the tension in a muscle that is only due to the passive resistance of elastic structures in the muscle, such as tendons and connective tissue. This tension is present even when the muscle is not actively contracting.

Therefore, both options A and D are correct. However, option A is a more commonly used and widely accepted definition.

Question 10

The corticospinal pathways

Accepted Answer

The corticospinal pathways are descending motor pathways that originate in the motor cortex of the brain and descend through the spinal cord to control voluntary movement.

Question 11

Afferent fibers from muscle spindle stretch receptors in a muscle make excitatory synaptic contact with motor neurons that innervate the extrafusal fibers of the same muscle.

Accepted Answer

This is true according to the concept of the stretch reflex, which is a reflexive response to muscle stretching that involves the activation of muscle spindle afferents and subsequent activation of motor neurons to contract the same muscle.

Question 12

Inhibitory input to motor neurons is as important for normal muscle function as excitatory input.

Accepted Answer

Inhibitory input to motor neurons helps to balance the activity of the excitatory input, allowing for precise control of muscle contraction and relaxation. Without inhibitory input, muscles would be constantly active and unable to perform fine movements or maintain a steady posture.

Question 13

Information from the muscle spindle stretch receptors is not conveyed above the level of the spinal cord and thus does not reach consciousness.

Accepted Answer

Information from the muscle spindle stretch receptors is conveyed to the brain via sensory nerve fibers and can reach consciousness.

Question 14

A young man is having trouble maintaining his posture after drinking too much at a party.The afferent pathways of the postural reflexes most likely affected in this man is the

Accepted Answer

The vestibular apparatus, located in the inner ear, plays a key role in maintaining balance and posture by providing information about head position and movement. Alcohol can affect the function of the vestibular system, leading to difficulty maintaining posture. The other options listed do not play a primary role in postural reflexes.

Question 15

The motor neuron pool of a skeletal muscle consists of the neurons of all of the motor units of that muscle.

Accepted Answer

The motor neuron pool of a skeletal muscle consists of the neurons of all of the motor units of that muscle.

Question 16

Why do people with Parkinson's disease experience resting tremors?

Accepted Answer

Resting tremors are a common symptom of Parkinson's disease, which is characterized by the degeneration of dopaminergic neurons in the substantia nigra. This results in a reduction of dopamine delivery to the basal ganglia and affects the regulation of motor control. The substantia nigra normally provides dopamine to the basal ganglia, which activates the sensorimotor cortex and initiates voluntary movements. Without sufficient dopamine, the activation of the sensorimotor cortex is reduced, leading to resting tremors.

Question 17

Stimulation of a Golgi tendon organ causes a reflex contraction of the muscle whose tension the receptor is monitoring.

Accepted Answer

Stimulation of a Golgi tendon organ actually causes a reflex relaxation of the muscle whose tension the receptor is monitoring, to prevent muscle damage from excessive tension.

Question 18

Once a planned movement is under way,it is usually carried out with no further modifications until it is finished.

Accepted Answer

The brain continuously monitors and can adjust movements as needed based on feedback from the body and environment, allowing for modifications during the execution of a planned movement.

Question 19

The activity of alpha motor neurons innervating an extensor muscle can be inhibited by activation of the Golgi tendon organs in the tendon that attaches that muscle to bone.

Accepted Answer

Golgi tendon organs are sensory receptors located in the tendons that detect tension generated by muscle contraction. When excessive tension is detected, they send inhibitory signals to the alpha motor neurons innervating the same muscle, leading to muscle relaxation and preventing potential damage to the tendon or muscle fibers. This is known as the Golgi tendon reflex.

Question 20

Which of the following symptoms is common following damage to the cerebellum?

Accepted Answer

Intention tremors are a common symptom following damage to the cerebellum.

Quiz 10: Control Body Movement