Question 1

The excitatory command to contract the biceps muscle of the arm is normally accompanied by an inhibitory command to relax the antagonist triceps muscle. If this inhibitory signal failed to occur,
A)the passive stretching of the triceps would trigger a stretch reflex that would return the arm to its original position.
B)the contraction of the biceps would be irreversible, and the limb would remain frozen in the resulting position.
C)the contraction of the biceps would cause tearing of fibers in the triceps and severe muscle damage.
D)the fibers that make up the triceps muscle would shorten and thicken during the resulting passive stretch.

Accepted Answer

The failure of the inhibitory signal to relax the antagonist triceps muscle would lead to both the biceps and triceps contracting simultaneously, resulting in an isometric contraction. However, the passive stretching of the triceps during this contraction would trigger a stretch reflex, which would cause the triceps to contract and the biceps to relax, returning the arm to its original position. This is a protective mechanism that prevents muscle damage and injury from occurring.

Question 2

The primary interaction of muscles and the nervous system involves the alpha motor neurons, which originate in the _______, exit through the _______, and terminate in the muscles.
A)brain; dorsal root
B)brain; ventral root
C)spinal cord; dorsal root
D)spinal cord; ventral root

Accepted Answer

Alpha motor neurons originate in the spinal cord, exit through the ventral root (also known as the anterior root), and terminate in the muscles. The brain also plays a role in muscle control, but specifically in relation to movement planning and coordination.

Question 3

Loss of blood flow in the _______ is the most common cause of hemiplegia.
A)anterior cerebral artery
B)vertebral artery
C)middle cerebral artery
D)circle of Willis

Accepted Answer

The middle cerebral artery is the most common site of occlusion leading to hemiplegia. It supplies blood to a large portion of the brain responsible for motor and sensory functions. Damage to this area can result in paralysis on one side of the body.

Question 4

The loss of a motor skill that cannot be attributed to hemiplegia, muscle weakness, sensory deficits, or motivation is called
A)hemiparesis.
B)hypermetria.
C)apraxia.
D)akinetopsia.

Accepted Answer

Apraxia is a motor disorder characterized by the loss of ability to perform purposeful movements or activities despite intact motor function, sensation, and understanding of the task. It cannot be attributed to hemiplegia, muscle weakness, sensory deficits, or motivation. Hypermetria refers to a condition where voluntary movements result in excessive movements, while akinetopsia pertains to the inability to perceive motion.

Question 5

Lesions to the pyramidal motor tract would produce difficulty in moving effectors on which side of the body?
A)the contralateral side
B)the ipsilateral side
C)both the contralateral and ipsilateral sides
D)neither the contralateral nor the ipsilateral side: the pyramidal neurons do not innervate effector muscles

Accepted Answer

Lesions to the pyramidal motor tract would produce difficulty in moving effectors on the contralateral side of the body. The pyramidal motor tract is responsible for controlling voluntary movements of the limbs and trunk on the opposite side of the body, meaning that a lesion on the left side of the motor cortex would affect movements on the right side of the body and vice versa.

Question 6

Single-cell recording studies have indicated that the _______ may be especially important in the control of internally guided motor sequences, whereas the _______ may be especially important in the control of externally guided motor sequences.
A)supplementary motor cortex; premotor cortex
B)premotor cortex; supplementary motor cortex
C)basal ganglia; cerebellum
D)cerebellum; basal ganglia

Accepted Answer

The supplementary motor cortex is involved in planning and coordinating internally generated movements, while the premotor cortex is more involved in movements that are guided by external stimuli.

Question 7

Corticospinal fibers originate primarily in the
A)cerebellum.
B)supplementary motor area.
C)premotor cortex.
D)primary motor cortex.

Accepted Answer

Corticospinal fibers originate primarily in the primary motor cortex.

Question 8

Hemiplegia is the
A)paralysis of the side of the body that is contralateral to the injured brain region.
B)paralysis of the side of the body that is ipsilateral to the injured brain region.
C)loss of sensory feedback from the side of the body that is contralateral to the injured brain region.
D)loss of sensory feedback from the side of the body that is ipsilateral to the injured brain region.

Accepted Answer

Hemiplegia specifically refers to paralysis of one entire side of the body, which is contralateral to the injured brain region. "Contra" refers to opposite sides of the body, so hemiplegia on the right side of the body indicates an injury to the left side of the brain and vice versa.

Question 9

Neurons in each half of the cerebellum synapse on _______ targets in the thalamus and other subcortical structures, and therefore regulate the effectors on the _______ side of the body.
A)ipsilateral; ipsilateral
B)ipsilateral; contralateral
C)contralateral; ipsilateral
D)contralateral; contralateral

Accepted Answer

The answer of Neurons in each half of the cerebellum...

Question 10

Which of the following is NOT an effector?
A)the brain
B)the jaw
C)the arm
D)the back

Accepted Answer

Effectors are structures in the body that respond to nervous system signals and produce a specific movement or action. The brain is not an effector as it is responsible for receiving sensory information and sending out signals to effectors such as muscles or glands.

Question 11

A laboratory dog has had surgery to separate the spinal components of its motor system from the cortical and subcortical components. Which of the following best describes the motor abilities of this animal?
A)The dog is able to sit and roll over in response to commands.
B)The dog can move proximal effectors normally, but not distal effectors.
C)The dog demonstrates reflexive withdrawal of its foot in response to sudden stimulation.
D)The dog is completely paralyzed from the neck down.

Accepted Answer

The separation of spinal components from cortical and subcortical components in the motor system would impair voluntary control over movements but would leave spinal reflexes, like the reflexive withdrawal of a foot in response to sudden stimulation, intact.

Question 12

One major difference between the pyramidal and the extrapyramidal motor tracts is their points of origin. The pyramidal tracts carry messages from _______ to the spinal cord, whereas the extrapyramidal tracts carry messages from _______ to the spinal cord.
A)cortical structures; subcortical structures
B)cranial nerves; peripheral nerves
C)basal ganglia; the cerebral cortex
D)subcortical structures; the cerebral cortex

Accepted Answer

The pyramidal tracts originate in cortical structures, specifically the primary motor cortex and the premotor cortex. The extrapyramidal tracts, on the other hand, originate in subcortical structures, specifically the basal ganglia and the brainstem.

Question 13

After suffering a focal brain injury, a patient has great difficulty in pantomiming particular motor actions such as turning a key in a lock. Because other problems like hemiplegia, muscle weakness, sensory deficits, and lack of motivation have been ruled out, your diagnosis would be
A)agnosia.
B)apraxia.
C)anomia.
D)akinetopsia.

Accepted Answer

The difficulty in pantomiming particular motor actions suggests apraxia, which is a disorder of voluntary movement that cannot be attributed to sensory, motor, or cognitive deficits. Agnosia refers to difficulty in recognizing objects, people, or sounds despite normal sensory function, anomia is difficulty in finding the right word when speaking or writing, and akinetopsia is a rare disorder that affects visual perception of motion.

Question 14

The pyramidal motor tract carries signals from the motor cortex of each cerebral hemisphere to _______ side(s) of the spinal cord, whereas the extrapyramidal motor tracts carry signals from various subcortical structures to _______ side(s) of the spinal cord.
A)the ipsilateral; both the ipsilateral and contralateral
B)both the ipsilateral and contralateral; the ipsilateral
C)the contralateral; both the ipsilateral and contralateral
D)both the contralateral and ipsilateral; the contralateral

Accepted Answer

The pyramidal motor tract primarily carries motor signals from the motor cortex to the contralateral side of the spinal cord, meaning it crosses over to the opposite side. The extrapyramidal motor tracts, on the other hand, originate from various subcortical structures and can project to both the ipsilateral and contralateral sides of the spinal cord, providing a more complex and less direct system of motor control.

Question 15

When a voluntary movement such as contracting one's right biceps is generated, what other signals, if any, must accompany this command?
A)A signal to antagonist muscles, such as the right triceps, to relax.
B)A signal to antagonist muscles, such as the right triceps, to flex simultaneously.
C)A signal to antagonist muscles, such as the left biceps, to relax.
D)No other signal is necessary.

Accepted Answer

When a voluntary movement is generated, the signal to the agonist muscle, in this case the right biceps, will also be accompanied by a signal to the antagonist muscle, in this case the right triceps, to relax, allowing the agonist muscle to contract without resistance. Therefore, choice A is the correct answer. Choice B is incorrect because contracting the antagonist muscle simultaneously would interfere with the movement of the agonist muscle. Choice C is incorrect because signaling the left biceps to relax is unrelated to the movement of the right biceps. Choice D is also incorrect because a signal to the antagonist muscle is necessary.

Question 16

The neurotransmitter responsible for translating action potentials into mechanical actions at muscles is
A)norepinephrine.
B)dopamine.
C)acetylcholine.
D)serotonin.

Accepted Answer

Acetylcholine is the neurotransmitter responsible for transmitting action potentials from neurons to muscle cells at the neuromuscular junction, leading to contraction of muscle fibers.

Question 17

Lesions to this region of the cerebellum lead to postural instability and difficulty in keeping one's eyes fixed on a visual object despite head or body movements.
A)the spinocerebellum
B)the vestibulocerebellum
C)the neocerebellum
D)the dentate nucleus

Accepted Answer

The region of the cerebellum responsible for maintaining postural stability and gaze fixation is the vestibulocerebellum, also known as the flocculonodular lobe. Lesions to this region can cause symptoms such as difficulty in maintaining balance and eye movements that are not synchronized with head movements. The spinocerebellum (choice A) is involved in coordinating movements of the limbs and trunk, while the neocerebellum (choice C) plays a role in planning and initiating voluntary movements. The dentate nucleus (choice D) is a deep cerebellar nucleus that receives input from the neocerebellum and is involved in the execution of movements.

Question 18

Which of the following is NOT a part of the basal ganglia?
A)the putamen
B)the claustrum
C)the caudate
D)the globus pallidus

Accepted Answer

The claustrum is a separate structure and not considered a part of the basal ganglia. The basal ganglia consists of the putamen, caudate, and globus pallidus.

Question 19

The term decussation refers to
A)a type of cerebrovascular accident that frequently damages motor structures.
B)the shift in involvement from the premotor cortex to the supplementary motor area (SMA) with motor learning.
C)the crossing of nerve fibers from one side of the body to the other.
D)a type of rapid involuntary movement made by people with Huntington's disease.

Accepted Answer

Decussation refers to the crossing of nerve fibers from one side of the body to the other. This occurs in several areas of the nervous system, including the spinal cord, brainstem, and thalamus. It allows for communication between the two hemispheres of the brain and for coordinated movement and sensation on the opposite sides of the body.

Question 20

Alpha motor neurons in the spinal cord communicate with muscle fibers by releasing acetylcholine, which influences muscle activity by
A)depolarizing neurons in the peripheral nervous system.
B)directly causing muscle contractions.
C)hyperpolarizing peripheral motor neurons.
D)inhibiting neurons in the dorsal root of the spinal cord.

Accepted Answer

Acetylcholine directly causes muscle contractions by binding to receptors on the muscle fibers, which leads to the activation of intracellular signaling pathways that result in muscle contraction.

Quiz 8: Action

The excitatory command to contract the biceps muscle of the arm is normally accompanied by an inhibitory command to relax the antagonist triceps muscle. If this inhibitory signal failed to occur,

The primary interaction of muscles and the nervous system involves the alpha motor neurons, which originate in the _, exit through the _, and terminate in the muscles.

Loss of blood flow in the _______ is the most common cause of hemiplegia.

The loss of a motor skill that cannot be attributed to hemiplegia, muscle weakness, sensory deficits, or motivation is called

Lesions to the pyramidal motor tract would produce difficulty in moving effectors on which side of the body?

Single-cell recording studies have indicated that the _ may be especially important in the control of internally guided motor sequences, whereas the _ may be especially important in the control of externally guided motor sequences.

Corticospinal fibers originate primarily in the

Hemiplegia is the

Neurons in each half of the cerebellum synapse on _ targets in the thalamus and other subcortical structures, and therefore regulate the effectors on the _ side of the body.

Which of the following is NOT an effector?

A laboratory dog has had surgery to separate the spinal components of its motor system from the cortical and subcortical components. Which of the following best describes the motor abilities of this animal?

One major difference between the pyramidal and the extrapyramidal motor tracts is their points of origin. The pyramidal tracts carry messages from _ to the spinal cord, whereas the extrapyramidal tracts carry messages from _ to the spinal cord.

After suffering a focal brain injury, a patient has great difficulty in pantomiming particular motor actions such as turning a key in a lock. Because other problems like hemiplegia, muscle weakness, sensory deficits, and lack of motivation have been ruled out, your diagnosis would be

The pyramidal motor tract carries signals from the motor cortex of each cerebral hemisphere to _ side(s) of the spinal cord, whereas the extrapyramidal motor tracts carry signals from various subcortical structures to _ side(s) of the spinal cord.

When a voluntary movement such as contracting one's right biceps is generated, what other signals, if any, must accompany this command?

The neurotransmitter responsible for translating action potentials into mechanical actions at muscles is

Lesions to this region of the cerebellum lead to postural instability and difficulty in keeping one's eyes fixed on a visual object despite head or body movements.

Which of the following is NOT a part of the basal ganglia?

The term decussation refers to

Alpha motor neurons in the spinal cord communicate with muscle fibers by releasing acetylcholine, which influences muscle activity by