module 4: movement

Question 1

What are reflexes?

Answer 1

Simple, unvarying, unlearned response to sensory stimuli such as touch, pressure, and pain

Reflexes are automatic responses that do not require conscious thought.

Question 2

Define motor plan or motor program.

Answer 2

Set of muscle commands established before the action occurs

Motor plans are essential for coordinating complex movements.

Question 3

What role does feedback play in motor planning?

Answer 3

Informs and fine-tunes the program as it unfolds

Feedback helps adjust movements for better accuracy and performance.

Question 4

What is the purpose of open-loop mechanisms?

Answer 4

Maximise speed with no external feedback; the activity is pre-programmed

Open-loop mechanisms are commonly used in ballistic movements.

Question 5

What do closed-loop mechanisms maximise?

Answer 5

Maximise accuracy

Closed-loop mechanisms rely on feedback from what is being controlled.

Question 6

Fill in the blank: Reflexes are a _______ response to sensory stimuli.

Answer 6

simple, unvarying, unlearned

Question 7

True or False: Closed-loop mechanisms do not require feedback.

Answer 7

False

Closed-loop mechanisms require feedback to adjust and refine movements.

Question 8

What type of movements are associated with open-loop mechanisms?

Answer 8

Ballistic movements

Ballistic movements are executed rapidly and without feedback.

Question 9

What are the levels of hierarchically organized motor control systems?

Answer 9

Levels of hierarchically organized motor control systems include:
* Skeletal system and attached muscles allow for movement
* Spinal cord controls skeletal muscles
* Brainstem integrates motor commands and relays sensory information
* Primary motor cortex initiates commands for action

These levels represent the organization of motor control from basic to complex functions.

Question 10

What system allows for movement in the body?

Answer 10

Skeletal system and attached muscles allow for movement

The skeletal system provides the structure for movement while the attached muscles facilitate the actual movement.

Question 11

Which part of the nervous system controls skeletal muscles?

Answer 11

Spinal cord controls skeletal muscles

The spinal cord plays a crucial role in transmitting signals between the brain and skeletal muscles.

Question 12

What is the role of the brainstem in motor control?

Answer 12

Brainstem integrates motor commands and relays sensory information

The brainstem is essential for coordinating reflexes and basic motor functions.

Question 13

Where are commands for action initiated in the brain?

Answer 13

Primary motor cortex initiates commands for action

The primary motor cortex is involved in planning and executing voluntary movements.

Question 14

What additional source of motor commands do nonprimary motor cortices provide?

Answer 14

Nonprimary motor cortices provide an additional source of motor commands.

Question 15

Which structures modulate the activities of motor control systems?

Answer 15

Cerebellum and basal ganglia modulate activities of motor control systems.

Question 16

What role does the thalamus play in motor control?

Answer 16

The thalamus is involved in a loop back to the cortex.

Question 17

What do tendons connect?

Answer 17

Tendons connect muscle to bone.

Question 18

How do muscles work in relation to each other?

Answer 18

Muscles work in antagonistic pairs—when one contracts, the other extends.

Question 19

What are muscles that act together called?

Answer 19

Synergists.

Question 20

What type of neurons transmit motor messages to muscles?

Answer 20

Motor neurons transmit motor messages to muscles.

Question 21

What are the two types of filaments found in skeletal muscle fibers?

Answer 21

• Thick filaments (myosin)
• Thin filaments (actin)

Question 22

What appearance do overlapping filaments give to skeletal muscle?

Answer 22

Striated appearance.

Question 23

What happens to the fiber length during muscle contraction?

Answer 23

Contraction shortens the fiber length.

Question 24

What are the two main types of striated muscle fibers?

Answer 24

• Fast-twitch muscle fibers
• Slow-twitch muscle fibers

Question 25

How do fast-twitch muscle fibers differ from slow-twitch muscle fibers?

Answer 25

Fast-twitch fibers contract rapidly but fatigue easily, while slow-twitch fibers contract more slowly but are resistant to fatigue.

Question 26

What does muscular dystrophy (MD) refer to?

Answer 26

Disorders that lead to degeneration and changes in muscle structure.

Question 27

What is dystrophin?

Answer 27

A protein needed for normal muscle function.

Question 28

On which chromosome is the gene for dystrophin encoded?

Answer 28

On the X chromosome.

Question 29

Why are males more likely to get muscular dystrophy?

Answer 29

Males have only one X chromosome, thus are much more likely to get the disease.

Question 30

What do motor neuron axons branch into near the target muscle?

Answer 30

Many terminals ## Footnote These terminals are where acetylcholine (ACh) is released.

Question 31

What is released by motor neuron terminals at the neuromuscular junction?

Answer 31

Acetylcholine (ACh) ## Footnote ACh is crucial for muscle contraction.

Question 32

Where does the axon terminate on the muscle fiber?

Answer 32

At neuromuscular junctions (NMJ) ## Footnote The NMJ is a specialized synapse for muscle activation.

Question 33

What is the characteristic of the NMJ in terms of action potentials?

Answer 33

Almost every action potential elicits a contraction ## Footnote This makes the NMJ an effective synapse.

Question 34

Define a motor unit.

Answer 34

A single motor neuron and all the muscle fibers it innervates ## Footnote When the neuron fires, all the fibers within that motor unit are stimulated.

Question 35

What is meant by innervation ratio?

Answer 35

The number of fibers innervated by one axon ## Footnote This ratio can vary significantly between different muscle types.

Question 36

What type of muscles have a low innervation ratio?

Answer 36

Muscles involved in fine movements ## Footnote Examples include muscles controlling eye movements or fingers.

Question 37

What type of muscles have a high innervation ratio?

Answer 37

Large muscles, e.g., in the leg ## Footnote These muscles are responsible for gross movements and strength.

Question 38

What are motor neurons?

Answer 38

The final common pathway through which brain and spinal cord control muscles.

Question 39

What neurotransmitter do motor neurons release?

Answer 39

ACh (Acetylcholine).

Question 40

Do motor neurons respond to other neurotransmitters?

Answer 40

Yes, they respond to a variety of transmitters, both excitatory and inhibitory.

Question 41

Are all motor neurons myelinated?

Answer 41

Yes, all motor neurons are myelinated for fast transmission.

Question 42

What is myasthenia gravis?

Answer 42

A condition that affects the communication between nerves and muscles.

Question 43

Define proprioception.

Answer 43

Perception of body movements and positions; essential for coordinating movement.

Question 44

What do muscle spindles monitor?

Answer 44

Muscle length.

Question 45

What do Golgi tendon organs monitor?

Answer 45

Muscle tension.

Question 46

What is the first step in the stretch reflex of an arm?

Answer 46

Weight is added.

Question 47

What happens when the muscle is stretched in the stretch reflex?

Answer 47

Muscle spindle afferents are excited.

Question 48

What do spindle afferents do after being excited?

Answer 48

Excite motor neurons.

Question 49

What is the final outcome of the stretch reflex?

Answer 49

Muscle is stimulated to oppose stretch.

Question 50

What do otherspinal circuits generate?

Answer 50

More complex, rhythmic locomotion ## Footnote These circuits can produce locomotion patterns without direct input from the brain.

Question 51

Can the rhythms generated by otherspinal circuits function independently?

Answer 51

Yes, they can function independently of brain influences or afferents ## Footnote This independence allows for the continuation of locomotor patterns even when brain activity is reduced.

Question 52

What is a central pattern generator?

Answer 52

Neural circuitry responsible for rhythmic behaviour, such as walking ## Footnote Central pattern generators are essential for generating the rhythmic patterns necessary for various forms of locomotion.

Question 53

What directly controls some muscles?

Answer 53

The brain ## Footnote Specifically, cranial motor nuclei in the brainstem innervate muscles of the head and neck.

Question 54

What type of cells are found in the cerebellar cortex?

Answer 54

Purkinje cells ## Footnote Purkinje cells only send inhibitory messages.

Question 55

How does the cerebellum guide movement?

Answer 55

Through inhibition ## Footnote The cerebellum is crucial for a wide variety of motor and nonmotor learning.

Question 56

What is a notable characteristic of individuals born without a cerebellum?

Answer 56

The plasticity of the developing brain compensates ## Footnote This indicates the brain's ability to adapt to such significant structural absence.

Question 57

What are the symptoms of Parkinson’s disease?

Answer 57

Tremors, loss of muscle tone, difficulty in motor movements ## Footnote These symptoms are linked to degeneration of dopamine-containing cells.

Question 58

Where do the dopamine-containing cells degenerate in Parkinson’s disease?

Answer 58

In the substantia nigra ## Footnote These cells project to the striatum.