Question 1

What is the best description of how a given muscle fiber can be inhibited from contracting?

Accepted Answer

A)   Inhibitory inputs from local reflexes and descending pathways prevent the fiber's motor neuron from firing action potentials.
B)   Descending inputs from brainstem components of the middle level of the motor control hierarchy make inhibitory synapses onto the muscle fibers.
C)   Contractions in an antagonistic muscle's fibers are stronger than the given muscle's contractions.
D)   Golgi tendon organs send afferent neurons directly to muscle fibers that attach to them and release inhibitory neurotransmitter.
E)   Interneurons in the local spinal cord region send axons to the muscle fiber's neuromuscular junction, where they impose presynaptic inhibition.F) A) and B)
G) B) and E)

Question 2

What is the definition of "muscle tone"?

Accepted Answer

A)   the resistance of muscle to continuous passive stretch
B)   the sound made by a muscle at rest
C)   the maximum contraction strength that a muscle is capable of
D)   the tension in a muscle that is only due to the passive resistance of elastic structures
E)   the average length of the muscle fibers in a given motor unitF) C) and E)
G) B) and D)

Question 3

Sensory neurons that are part of the stretch reflex synapse directly onto the motor neurons of antagonist muscles, and inhibit them.

Accepted Answer

A) True 
 B)False

Question 4

The corticospinal pathways:

Accepted Answer

A)   are descending motor pathways.
B)   begin in the cortex of the cerebellum.
C)   consist of many interneurons linked synaptically.
D)   are composed of alpha motor neurons.
E)   bring sensory information from the spinal cord to the somatosensory region of the cerebral cortex.F) A) and C)
G) A) and E)

Question 5

According to the hierarchy of motor control,

Accepted Answer

A)   the highest level of control consists entirely of neurons in the primary motor region of the cerebral cortex.
B)   the middle level of control does not involve any areas of the cerebral cortex.
C)   the local level of control includes the cerebellum and basal nuclei.
D)   structures in the middle level receive information from both the higher and the local levels of the hierarchy.
E)   afferent information from skin, joint, and muscle receptors cannot modify a movement once it has been initiated by a motor program from the middle level of the hierarchy.F) A) and B)
G) B) and E)

Question 6

Afferent pathways of the postural reflexes come mainly from:

Accepted Answer

A)   the cerebellum.
B)   the eyes, the vestibular apparatus, and the receptors involved in proprioception.
C)   muscle spindles and temperature receptors.
D)   nociceptors and chemoreceptors.
E)   the somatosensory cortex.F) A) and B)
G) D) and E)

Question 7

Crossed-extensor reflexes, but not stretch reflexes, are important postural reflexes.

Accepted Answer

A) True 
 B)False

Question 8

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

Accepted Answer

A) True 
 B)False

Question 9

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

Accepted Answer

A)   The body leans so that the center of gravity shifts over the foot that is lifted off the ground.
B)   The body only accelerates forward, so the center of gravity remains directy between the two feet.
C)   The body accelerates forward, but the center of gravity shifts over the foot that is lifted off the ground.
D)   The body leans so that the center of gravity shifts over the foot that is on the ground.
E)   The center of mass is left behind by the acceleration of the body, so the body must lean forward to compensate.F) A) and E)
G) A) and D)

Question 10

In general, the brainstem descending pathways have greater influence over motor neurons controlling muscles involved in fine movements and the corticospinal pathways are more involved in the coordination of large muscle groups and postural muscles.

Accepted Answer

A) True 
 B)False

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

What is the function of the basal nuclei in normal motor control?

Accepted Answer

A)   They provide a perceptual awareness related to specific sensory inputs from the eyes, nose, and mouth.
B)   They provide a general perceptual awareness associated with somatosensory inputs from the skin, muscles, and joints.
C)   They provide a sense of the cause-and-effect relationships between muscle actions and the consequences of taking these actions before executing them.
D)   They participate in a looping neuronal circuit through which motor impulses are sent to facilitate or suppress movements.
E)   They form an initial intention to move, such as when you decide to pick up an object.F) A) and C)
G) A) and B)

Question 13

Which best describes the specific cause of Parkinson disease?

Accepted Answer

A)   enhanced sensitivity of cholinergic receptors to acetylcholine
B)   reduced ability of neurons in the substantia nigra to release dopamine
C)   failure of serotonin receptors to bind with these neurohormones
D)   hyperactivity of metabolic enzymes that degrade dopamine
E)   natural tendency of basal nuclei to follow a daily recurring, oscillating cycle of rising and falling norepinephrine releaseF) C) and E)
G) A) and B)

Question 14

The skeletal muscles of the body are represented in the primary motor cortex proportionately to their size.

Accepted Answer

A) True 
 B)False

Question 15

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

Accepted Answer

A) True 
 B)False

Question 16

Motor pathways extending from the central nervous system to muscle fibers are subject to control by both excitatory and inhibitory interneurons.

Accepted Answer

A) True 
 B)False

Question 17

Which is TRUE about the function of the cerebellum?

Accepted Answer

A)   It helps to coordinate body movements.
B)   It is important in maintaining posture.
C)   It receives input from sensory pathways.
D)   It stores the memory of motor movements that involve several joints.
E)   All of the choices are correct.F) A) and C)
G) D) and E)

Question 18

Which is a symptom of Parkinson disease?

Accepted Answer

A)   flaccid paralysis
B)   intention tremor
C)   resting tremor
D)   memory loss
E)   loss of proprioceptionF) A) and E)
G) A) and C)

Question 19

The flexor (withdrawal)  reflex

Accepted Answer

A)   has a monosynaptic component.
B)   is initiated by stretching muscle spindle fibers.
C)   is initiated by stimulation of the Golgi tendon organ.
D)   stimulates contraction of the ipsilateral flexor muscle and inhibits contraction of the ipsilateral extensor muscle.
E)   stimulates contraction of the contralateral flexor muscle and inhibits contraction of the contralateral extensor muscle.F) A) and B)
G) B) and E)

Question 20

Which is NOT true about reflexes initiated by muscle spindle activation?

Accepted Answer

A)   They have a monosynaptic component.
B)   They result in activation of alpha motor neurons.
C)   They result in activation of extrafusal muscle fibers.
D)   The "knee-jerk" reflex is an example.
E)   They inhibit the activation of muscles that are stretched.F) A) and B)
G) B) and E)

Exam 10: Control of Body Movement

What is the function of the basal nuclei in normal motor control?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is the best description of how a given muscle fiber can be inhibited from contracting?

Correct AnswerverifiedShow Answer

The flexor (withdrawal) reflex

Correct AnswerverifiedShow Answer

In general, the brainstem descending pathways have greater influence over motor neurons controlling muscles involved in fine movements and the corticospinal pathways are more involved in the coordination of large muscle groups and postural muscles.

Correct AnswerverifiedShow Answer

Which best describes the specific cause of Parkinson disease?

Correct AnswerverifiedShow Answer

Motor pathways extending from the central nervous system to muscle fibers are subject to control by both excitatory and inhibitory interneurons.

Correct AnswerverifiedShow Answer

What is the definition of "muscle tone"?

Correct AnswerverifiedShow Answer

According to the hierarchy of motor control,

Correct AnswerverifiedShow Answer

The corticospinal pathways:

Correct AnswerverifiedShow Answer

Which is a symptom of Parkinson disease?

Correct AnswerverifiedShow Answer

Which is TRUE about the function of the cerebellum?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The skeletal muscles of the body are represented in the primary motor cortex proportionately to their size.

Correct AnswerverifiedShow Answer

Sensory neurons that are part of the stretch reflex synapse directly onto the motor neurons of antagonist muscles, and inhibit them.

Correct AnswerverifiedShow Answer

Crossed-extensor reflexes, but not stretch reflexes, are important postural reflexes.

Correct AnswerverifiedShow Answer

Which is NOT true about reflexes initiated by muscle spindle activation?

Correct AnswerverifiedShow Answer

Afferent pathways of the postural reflexes come mainly from:

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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