Motor Systems: Structure and Function - Physiology for Doctor of Medicine

Question 1

The corticospinal tract originates in the:

Accepted Answer

Motor cortex

Answer

Premotor cortex

Answer

Frontal eye field

Answer

Supplementary motor area

Question 2

Which neurotransmitter acts as the primary excitatory neurotransmitter in the spinal cord?

Accepted Answer

Glutamate

Answer

Glycine

Answer

GABA

Answer

Serotonin

Question 3

The cerebellar vermis is primarily responsible for:

Accepted Answer

Coordination of axial and proximal limb movements

Answer

Coordination of eye movements

Answer

Control of fine motor movements

Answer

Balance and equilibrium

Question 4

The contraction of a skeletal muscle in the stretch reflex is primarily mediated by which interneurons in the spinal cord?

Accepted Answer

Ia excitatory interneurons

Answer

Ia inhibitory interneurons

Answer

Ib inhibitory interneurons

Answer

Ib excitatory interneurons

Question 5

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

Accepted Answer

Initiation of movement

Answer

Control of movement speed and direction

Answer

Planning and sequencing of complex movements

Answer

Maintenance of muscle tone

Question 6

A motor unit refers to the:

Accepted Answer

Axon of a motor neuron and all the muscle fibers it innervates

Answer

Dendrites of a motor neuron and all the sensory receptors it innervates

Answer

Cell body of a motor neuron and the glial cells that surround it

Answer

Myelin sheath of a motor neuron and the blood vessels that supply it

Question 7

Distinguish between alpha and gamma motor neurons based on their target muscle fibers and functional roles.

Accepted Answer

Alpha motor neurons innervate extrafusal fibers, controlling muscle contraction; Gamma motor neurons innervate intrafusal fibers, adjusting muscle spindle sensitivity.

Answer

Alpha motor neurons are excitatory, while gamma motor neurons are inhibitory.

Answer

Alpha motor neurons are myelinated, whereas gamma motor neurons are unmyelinated.

Answer

Alpha motor neurons belong to the somatic nervous system, while gamma motor neurons belong to the autonomic nervous system.

Question 8

Which of the following is ***not a component*** of the spinal cord?

Accepted Answer

Cerebellum

Answer

Gray matter

Answer

White matter

Answer

Spinal nerve roots

Question 9

Which of the following is responsible for fine motor control and coordination?

Accepted Answer

Cerebellum

Answer

Cerebrum

Answer

Spinal cord

Answer

Brainstem

Question 10

The spinal reflex arc involves all of the following ***except***:

Accepted Answer

Higher brain centers

Answer

Stimulus

Answer

Receptor

Answer

Effector

Question 11

The motor cortex is located in which lobe of the brain?

Accepted Answer

Frontal

Answer

Parietal

Answer

Temporal

Answer

Occipital

Question 12

Which of the following hormones promotes muscle growth and repair?

Accepted Answer

Testosterone

Answer

Estrogen

Answer

Progesterone

Answer

Adrenaline

Question 13

The sliding filament theory of muscle contraction explains the interaction between:

Accepted Answer

Actin and myosin

Answer

Tropomyosin and troponin

Answer

Calcium ions and calmodulin

Answer

Myosin and ATP

Question 14

Which structure is primarily responsible for coordinating movement and maintaining balance?

Accepted Answer

Cerebellum

Answer

Cerebral cortex

Answer

Brainstem

Answer

Spinal cord

Question 15

At what level of the brainstem does the decussation of motor tracts occur?

Accepted Answer

Medulla oblongata

Answer

Pons

Answer

Midbrain

Answer

Spinal cord

Question 16

Which neurotransmitter is released at the junction between a motor neuron and a muscle fiber?

Accepted Answer

Acetylcholine

Answer

Dopamine

Answer

Serotonin

Answer

GABA

Question 17

What is the primary role of alpha motor neurons in the motor system?

Accepted Answer

Trigger muscle contraction

Answer

Transmit sensory information to the spinal cord

Answer

Control autonomic functions

Answer

Regulate neurotransmitter release

Question 18

What reflex arc is responsible for the rapid withdrawal of a limb from a painful stimulus?

Accepted Answer

Withdrawal reflex

Answer

Flexor reflex

Answer

Crossed extensor reflex

Answer

Stretch reflex

Question 19

Which type of muscle fiber is known for its slow contractions and sustained endurance?

Accepted Answer

Type I

Answer

Type IIa

Answer

Type IIb

Answer

Type IIx

Question 20

Which motor disorder is characterized by rigidity, bradykinesia, and tremor?

Accepted Answer

Parkinson's disease

Answer

Alzheimer's disease

Answer

Multiple sclerosis

Answer

Huntington's disease

Question 21

Which of the following is NOT a function of the spinal cord?

Accepted Answer

Initiate voluntary movement

Answer

Transmit motor signals from the brain to the muscles

Answer

Transmit sensory signals from the body to the brain

Answer

Control reflexes

Question 22

Which of the following cranial nerves is responsible for controlling eye movements?

Accepted Answer

Trochlear nerve

Answer

Olfactory nerve

Answer

Optic nerve

Answer

Trigeminal nerve

Question 23

Which of the following neurotransmitters is primarily responsible for muscle contraction?

Accepted Answer

Acetylcholine

Answer

Dopamine

Answer

Serotonin

Answer

Norepinephrine

Question 24

Which of the following structures is responsible for maintaining balance and equilibrium?

Accepted Answer

Vestibular system

Answer

Auditory system

Answer

Gustatory system

Answer

Olfactory system

Question 25

Which of the following is NOT a component of the motor cortex?

Accepted Answer

Broca's area

Answer

Primary motor cortex (M1)

Answer

Premotor cortex (PM)

Answer

Supplementary motor area (SMA)

Question 26

Which of the following is NOT a function of the cerebellum?

Accepted Answer

Planning and initiation of movement

Answer

Coordination of movement

Answer

Balance and equilibrium

Answer

Regulation of muscle tone

Question 27

What is a primary function of the cerebellum in motor control?

Accepted Answer

Coordinating and smoothing movements

Answer

Initiating voluntary movements

Answer

Processing sensory information from the body

Answer

Planning and executing complex movement sequences

Question 28

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

Accepted Answer

Cerebellum

Answer

Caudate nucleus

Answer

Globus pallidus

Answer

Substantia nigra

Question 29

Which of the following structures is NOT a component of the motor system?

Accepted Answer

Thalamus

Answer

Spinal cord

Answer

Brainstem

Answer

Cerebellum

Question 30

Which of the following neurotransmitters is primarily responsible for transmitting excitatory signals in the motor system?

Accepted Answer

Glutamate

Answer

GABA

Answer

Glycine

Answer

Serotonin

Question 31

Which of the following muscles is the prime mover in elbow flexion?

Accepted Answer

Biceps brachii

Answer

Triceps brachii

Answer

Brachioradialis

Answer

Anconeus

Question 32

Which part of the cerebellum is primarily responsible for maintaining balance and coordinating eye movements?

Accepted Answer

Flocculonodular lobe

Answer

Cerebellar vermis

Answer

Cerebellar hemispheres

Answer

Dentate nucleus

Question 33

Which of the following is the primary function of the corticospinal tract?

Accepted Answer

To transmit motor signals from the cerebral cortex to the spinal cord

Answer

To transmit sensory information from the spinal cord to the cerebral cortex

Answer

To regulate autonomic functions

Answer

To control eye movements

Question 34

Which of the following conditions is characterized by a lack of muscle tone and impaired voluntary movement?

Accepted Answer

Flaccidity

Answer

Spasticity

Answer

Rigidity

Answer

Tremor

Question 35

Which of the following muscles is supplied by the trigeminal nerve (cranial nerve V)?

Accepted Answer

Masseter

Answer

Frontalis

Answer

Orbicularis oris

Answer

Sternocleidomastoid

Question 36

Which of the following techniques is used to measure the electrical activity of the brain?

Accepted Answer

Electroencephalography (EEG)

Answer

Electromyography (EMG)

Answer

Positron emission tomography (PET)

Answer

Magnetic resonance imaging (MRI)

Question 37

What pathway carries motor commands from the brain and spinal cord to the muscles?

Accepted Answer

Efferent pathway

Answer

Afferent pathway

Answer

Interneuron pathway

Answer

Reflex arc

Question 38

Which of the functions below does NOT belong to the cerebellum?

Accepted Answer

Regulation of blood pressure

Answer

Coordination of movement

Answer

Balance and equilibrium

Answer

Motor learning

Question 39

Neurons in the anterior horn of the spinal cord are responsible for:

Accepted Answer

Transmitting motor signals to muscles

Answer

Receiving sensory signals from the skin

Answer

Transmitting pain signals to the brain

Answer

Controlling autonomic functions

Question 40

Which neurotransmitter is released at the neuromuscular junction to stimulate muscle contraction?

Accepted Answer

Acetylcholine

Answer

Epinephrine

Answer

Dopamine

Answer

Serotonin

Question 41

In which lobe of the brain is the primary motor cortex located?

Accepted Answer

Frontal lobe

Answer

Parietal lobe

Answer

Occipital lobe

Answer

Temporal lobe

Question 42

Which type of muscle fiber is responsible for sustained, low-force contractions?

Accepted Answer

Type I

Answer

Type IIa

Answer

Type IIb

Answer

Type IIx

Question 43

The stretch reflex is mediated by which type of neural pathway?

Accepted Answer

Monosynaptic pathway

Answer

Polysynaptic pathway

Answer

Direct pathway

Answer

Indirect pathway

Question 44

Which neurodegenerative condition primarily affects motor neurons?

Accepted Answer

Amyotrophic lateral sclerosis (ALS)

Answer

Parkinson's disease

Answer

Alzheimer's disease

Answer

Multiple sclerosis

Question 45

In which cortical region is the motor homunculus located?

Accepted Answer

Primary motor cortex

Answer

Primary sensory cortex

Answer

Secondary motor cortex

Answer

Prefrontal cortex

Question 46

Which component is the largest part of the extrapyramidal system?

Accepted Answer

Basal ganglia

Answer

Cerebellum

Answer

Red nucleus

Answer

Substantia nigra

Question 47

A patient presents with difficulty initiating voluntary movements, a resting tremor, and muscle rigidity. Dysfunction in which of the following structures is most likely responsible for these symptoms?

Accepted Answer

Basal ganglia

Answer

Spinal cord

Answer

Cerebellum

Question 48

Damage to the corticospinal tract is most likely to result in which of the following clinical presentations?

Accepted Answer

Weakness and spasticity in the muscles on the opposite side of the body

Answer

Tremor in the limbs on the same side of the body

Answer

Loss of sensation of position and movement in the limbs on the same side of the body

Question 49

Which neurotransmitter is the primary means of communication between motor neurons and skeletal muscle fibers?

Accepted Answer

Acetylcholine

Answer

Glutamate

Answer

GABA

Answer

Dopamine

Question 50

A patient with a cerebellar lesion is most likely to exhibit which of the following motor deficits?

Accepted Answer

Ataxia and dysmetria

Answer

Muscle spasticity and exaggerated reflexes

Answer

Muscle weakness and wasting

Answer

Resting tremor and muscle rigidity

Question 51

Which of the following best describes the brainstem's primary functions in motor control?

Accepted Answer

Relaying motor commands from the cortex to the spinal cord and controlling essential reflexes

Answer

Fine-tuning movements and maintaining balance

Answer

Initiating voluntary movement

Question 52

What is the primary role of the dorsal root ganglia in motor control?

Accepted Answer

They house sensory neuron cell bodies that relay information about muscle position and movement to the spinal cord.

Answer

They contain motor neuron cell bodies that transmit signals to skeletal muscles.

Question 53

Damage to lower motor neurons is most likely to result in which of the following clinical findings?

Accepted Answer

Muscle weakness, atrophy, and fasciculations

Answer

Muscle spasticity and exaggerated reflexes

Answer

Resting tremor and muscle rigidity

Answer

Loss of balance and coordination

Question 54

Which of the following best describes the principle of reciprocal inhibition in motor control?

Accepted Answer

The simultaneous contraction of one muscle and relaxation of its opposing muscle

Answer

The activation of multiple motor units to increase muscle force

Answer

The gradual increase in muscle force with repeated stimulation

Question 55

What constitutes a motor unit?

Accepted Answer

A single motor neuron and all the muscle fibers it innervates

Answer

A group of motor neurons that innervate the same muscle

Answer

A functional unit of the cerebellum responsible for coordination

Question 56

Which of the following is NOT a component of the extrapyramidal system?

Accepted Answer

Corticospinal tract

Answer

Red nucleus

Answer

Substantia nigra

Answer

Basal ganglia