Voluntary Control of Movement

Question 1

What are the most important functions of motor control?

Answer 1

Conducting voluntary actions. (Lots of reflex control feeds into smooth patterned movement such as that seen in response to a nearby explosion)

Adjusting body posture to provide stable background for movement. (Other systems feed into it like vestibules and vision)

Coordinate action of various muscles to make movements smooth and precise. (Motor learning can be stored and brought about. Stored in the cerebellum and basal ganglia)

Question 2

What does the basal ganglia do to a thought about an action?

Answer 2

It refines it so that it translates into an appropriate action.

Question 3

What does the cerebellum do to a thought about an action?

Answer 3

(i.e Evaluates a thought with what we are currently doing. )

Question 4

What does the cerebellum do to a thought about an action?

Answer 4

(i.e Evaluates a thought with what we are currently doing.)

Question 5

What is the role of the spinal cord in motor control?

Answer 5

Controls local movement patterns and reflexes.

Question 6

What is the role of the brainstem in motor control?

Answer 6

Maintains tone

Continuous modification of tone in different muscles

Question 7

What is the role of the cortex in motor control?

Answer 7

Issues sequential commands and is important for complex patterns and practiced movements.

Question 8

What is the role of the cerebellum in motor control?

Answer 8

Motor planning, coordination, and assessment. It modulates and coordinates postural movements and accessory motor function.

It also provides predictive patterns of movement

Question 9

What is the role of the basal ganglia in motor control?

Answer 9

Helps cortex execute subconscious learned patterns of movement.

It also helps plan multiple parallel and sequential patterns of movement

Question 10

What are the 3 phases of motor control?

Answer 10

Strategy (What to do)

Tactics (How to do it)

Execution (Doing it)

Question 11

What controls strategy in the hierarchy of motor control?

Answer 11

Prefrontal cortex

Posterior parietal cortex

Basal ganglia

Question 12

What controls tractics in the hierarchy of motor control?

Answer 12

Pre-motor cortex and supplementary motor area

Cerebellum

Question 13

What controls execution in the hierarchy of motor control?

Answer 13

Primary motor cortex

Brain stem

Spinal cord

Question 14

What happens in the primary motor cortex and where does the input occur?

Answer 14

Primary motor cortex is the point of no return where an action is initiated. It receives input from supp. motor area.

Patterns are assembled in supplementary motor area after receiving input from everywhere else.

Question 15

What are the direct control pathways of movement?

Answer 15

Corticospinal tract (most important)

Rubrospinal tract

Question 16

What does it mean to say direct control pathway?

Answer 16

Direct pathway from the cortex to the spinal cord

Question 17

In the corticospinal tract where does the UMN terminate?

Answer 17

In the spinal cord at the level of decussation.

Question 18

Where are the UMNs located in the rubrospinal tract?

Answer 18

2 UMNs in relay are present in the brain one starts at the motor cortex and the other starts at the red nucleus

Question 19

What muscles do the nerves of the corticospinal tract innervate?

Answer 19

Lateral corticospinal tract innervates distal limb muscles which influence fine movement, coordination and skills.

Ventral corticospinal tract innervates proximal limb muscles and provides innervation for gross movement.

Question 20

Why does lateral corticospinal tract contain 80% of nerve fibers?

Answer 20

It provides innervation for more complex movements compared to the 20% that innervates proximal limb muscles which don’t need to be as complex.

Question 21

What does the rubrospinal tract do?

Answer 21

It’s an accessory route for transmission of signals.

It innervates distal limb muscles and provides innervation for fine movements and control.

Question 22

Where does the tectospinal tract start and go to?

Answer 22

Starts at superior colliculi of brainstem and descends through spinal cord.

Question 23

What does the tectospinal tract do?

Answer 23

Receives visual input and provides output to muscles of the head and neck.

Question 24

What do Vestibular nuclei do?

Answer 24

Receive input from the vestibules of our ear detecting equilibrium. Fibers then descent through spinal cord, our cerebellum, and our pontine reticular nuclei resulting in adjustments to postural adjustments.

Question 25

What are reticular nuclei hooked up to?

Answer 25

The reticular formation in our brain and monitoring activity in our brain and they excite antigravity muscles.

Question 26

What kind of adjustments can be derived from the medial indirect tracts?

Answer 26

Reticulospinal tract adjusts rigidity of muscles

Vestibulospinal tract adjusts for gravity and equilibrium

Tectospinal tract adjusts for visual cues.

Question 27

Where does the reticulospinal tract get its input from?

Answer 27

Vestibule

Cerebellum

Lateral hypothalamus

Globus pallidus

Sensorimotor cortex

Question 28

Where does output from the reticulospinal tract go?

Answer 28

The pontine RST is excitatory and excites axial and extensor function.

The medullary RST is inhibitory and inhibits extensor muscles and excites flexor muscles.

Question 29

Which part of the brain adjusts movements to make them align with the intended movement?

Answer 29

The cerebellum

Question 30

What happens if there is a lesion to the cerebellum?

Answer 30

Coordination is lost without paralysis.

Ataxia

Dysynergia: Losing synergistic multijoint movements

Dysmetria: Overshooting or undershooting target

Question 31

Where does the cerebellum get its input?

Answer 31

From brain via cortical motor control outputs, vestibule (balance and hearing), basal ganglia and spinal cord.

From periphery cerebellum gets information from dorsol spinocerebellar tract (spindles and GTOs), spinal cord anterior horns via ventral spinocerebellar tract

Question 32

Which cerebellar nuclei are important for balance and eye movements?

Answer 32

Vestibular nuclei from vestibulocerebellum.

Question 33

Which cerebellar nuclei are important for motor planning?

Answer 33

Dentate nucleus which projects information from lateral hemispheres (cerebrocerebellum) to the cerebrum.

Question 34

Which cerebellar nuclei are important for motor execution?

Answer 34

Fastigial nucleus (medial descending systems)

Interposed nuclei (lateral descending systems)

Question 35

What does the spinocerebellum do?

Answer 35

Adjusts ongoing movements (limb muscles)

Question 36

What does the cerebrocerebellum do?

Answer 36

Pays attention to motor planning of sequential limb movements.

Question 37

Which of the parts of the cerebellum can be largely replaced by the basal ganglia?

Answer 37

The cerebrocerebellum