Motor Control 1

Question 1

Voluntary movement uses a functional hierarchy with 3 levels, what are these 3 levels?

Answer 1

Question 2

What is the function of the high level of the functional hierarchy of voluntary movements?

Answer 2

Strategy

Question 3

What is the function of the middle level of the functional hierarchy of voluntary movements?

Answer 3

Tactics

Question 4

What is the function of the low level of the functional hierarchy of voluntary movements?

Answer 4

Execution

Question 5

What structures are involved in the high level of the functional hierarchy of voluntary movements?

Answer 5

Association neocortex

Basal ganglion

Question 6

What structures are involved in the middle level of the functional hierarchy of voluntary movements?

Answer 6

Motor cortex

Cerebellum

Question 7

What structures are involved in the low level of the functional hierarchy of voluntary movements?

Answer 7

Brain stem

Spinal cord

Question 8

What does strategy mean in terms of voluntary movements?

Answer 8

The goal and the movement strategy to best achieve this goal

Question 9

What does tactics mean in terms of voluntary movement?

Answer 9

The sequence of spatiotemporal muscle contractions to achieve a goal smoothly and accurately

Question 10

What does exectution mean in terms of voluntary movements?

Answer 10

Activation of motor neuron and interneuron pools to generate goal-directed movement

Question 11

How is the brain connected to the spinal cord?

Answer 11

Lateral pathways

Ventromedial pathways

Question 12

What do lateral pathways of the spinal cord control?

Answer 12

Voluntary movement of distal muscles

Question 13

Lateral pathways of the spinal cord are under the control of what?

Answer 13

Direct cortical control

Question 14

What do ventromedial pathways control?

Answer 14

Posture and locomotion

Question 15

Ventromedial pathways of the spinal cord are under control by what?

Answer 15

Brain stem control

Question 16

What are examples of lateral pathways?

Answer 16

Corticospinal tract

Rubrospinal tract

Question 17

What are examples of vestromedial pathways?

Answer 17

Vestibulospinal tract

Tectospinal tract

Pontine reticulospinal tract

Medullary reticulospinal tract

Question 18

What does CST stand for?

Answer 18

Corticospinal tract

Question 19

What does RST stand for?

Answer 19

Rubrospinal tract

Question 20

What is the longest and largest tract of the spinal cord?

Answer 20

Corticospinal tract (CST), with about 1 million axons

Question 21

Where does the corticospinal tract originate?

Answer 21

2/3 in areas 4 and 6 of the fontal motor cortex

Rest is somatosensory

Question 22

Does the corticospinal tract decusscate? And if so, where does this occur?

Answer 22

Yes it does, at the medulla/spinal cord junction so the right motor cortex controls the left side and vice versa

Question 23

Where do axons of the corticospinal tract synapse?

Answer 23

Ventral horn motor neurons and interneurons to control muscles voluntarily

Question 24

Where does the rubrospinal tract originate?

Answer 24

Red nucleus of midbrain and receives inputs from same cortical areas as CSF (2/3 if areas 4 and 6 of frontal motor cortex, rest is somatosensory)

Question 25

What do lesions of the corticospinal and rubrospinal tracts cause?

Answer 25

Fine movement of arms and hands lost Cannot move shoulders, elbows, wrist and fingers independently

Question 26

What happens if lesions only occur in the corticospinal tract and not both the corticospinal and rubrospinal tract?

Answer 26

Deficits are seen for a few months, then functions reappear as they are taken over by the rubrospinal tract

Question 27

For the rubrospinal tract, what side of the brain controls what side of the body?

Answer 27

Decussates above between medulla and midbrain so controls contralateral half of body

Question 28

What does the corticospinal tract control in the spinal cord?

Answer 28

Pools of motor neurons (monosynaptically excite pool of agonist motoneurons whilst via interneurons inhibit pools of antagonist motoneurons)

Question 29

What projects via the corticospinal tract to pools of motoneurons in the spinal cord?

Answer 29

Large pyramidal neurons in motor cortex

Question 30

What is the function of the vestibulospinal tract?

Answer 30

Stabilises head and neck

Question 31

What does VST stand for?

Answer 31

Vestibulospinal tract

Question 32

What is the function of the tectospinal tract?

Answer 32

Ensures eye reamins stable as the body moves

Question 33

What does TST stand for?

Answer 33

Tectospinal tract

Question 34

Where do the poutine and medullary reticulospinal tracts originate?

Answer 34

Brainstem

Question 35

What are the functions of the poutine and medullary reticulospinal tracts?

Answer 35

Use sensory information about balance, body position and vision Reflexly maintain balance and body position Innervate trunk and antigravity muscles in limbs

Question 36

What pathways does voluntary movement require input from?

Answer 36

Motor cortex via lateral pathways

Question 37

What nuclei is found between the motor cortex and the spinal cord for vestromedial pathways?

Answer 37

Reticular nuclei Superior colliculus and vestibular nuclei

Question 38

What areas of the brain plana nd control precise voluntary movements?

Answer 38

Primary motor cortex and pre-motor areas

Question 39

What do upper motor neurons target to form?

Answer 39

Lower motor neurons in the spinal cord to form circuits, some of which control reflexes such as stretch reflex

Question 40

Where are upper motor neurons found?

Answer 40

Cortex Brainstem

Question 41

What can the distribution of lower motor neurons be described as?

Answer 41

Somatotopic

Question 42

What does somatotopic mean?

Answer 42

Point-for-point correspondence of an area of the body to a specific point on the CNS

Question 43

What do medial lower motor neurons control?

Answer 43

Axial and proximal muscles

Question 44

What do lateral lower motor neurons control?

Answer 44

Distal limb muscles

Question 45

What do white matter tracts differ in?

Answer 45

Origin and function

Question 46

What do medial tracts from the brainstem down the spinal cord control?

Answer 46

Posture and balance and orienting mechanism

Question 47

What do lateral tracts from the brainstem down the spinal cord control?

Answer 47

Skilled voluntary movement

Question 48

Where are the upper motor neurons that are the beginning of lateral white matter of spinal cord?

Answer 48

Cerebral cortex of contralateral side

Question 49

Where are upper motor neurons that are the origin of anterior-medial white matter of spinal cord?

Answer 49

Brainstem

Question 50

What Brodmann area is the primary motor cortex?

Answer 50

Area 4

Question 51

Where is the primary motor cortex (what gyrus)?

Answer 51

Precentral gyrus

Question 52

What does PMA stand for?

Answer 52

Pre-motor area

Question 53

What does SMA stand for?

Answer 53

Supplementary motor area

Question 54

What broddman area is the premotor and supplementary motor areas?

Answer 54

Areas 6

Question 55

For movement, what does the cerebral cortex need to know?

Answer 55

Where the body is in space Where it wants to go Plan to get there (these 3 things are functions of different areas of the cortex)

Question 56

What are some examples of areas of the brain involved in planning and instructing voluntary movement?

Answer 56

Prefrontal cortex Area 6 (SMA and PMA) Area 4 (M1) Central sulvus S1 Posterior parietal cortex (area 5 and area 7)

Question 57

What does M1 stand for?

Answer 57

Motor cortex

Question 58

From medial to lateral, what body parts are arranged in the somatotopic organisation of the primary motor cortex?

Answer 58

Toes \> legs up to shoulder \> shoulder to fingers (little to thumb) \> top of head to bottom of head \> tongue then swallowing

Question 59

What is an example of a physical display of the presents of somatotopic maps?

Answer 59

Epileptic seizures often 'march' across the body, beginning with abnormal fingers movements then hand, then arm, shoulder, finally face

Question 60

What is used in epileptics to decide which brain areas to be spared surgically?

Answer 60

Penfield electrical stimulation

Question 61

What does the SMA do?

Answer 61

Innervates distal motor units directly

Question 62

What does the PMA do?

Answer 62

Connects with reticulospinal neurons innervating proximal motor neurons

Question 63

Explain the process of originating and coordinating body movements?

Answer 63

1) Mental image of body in space is generated by somatosensory, proprioceptive and visual inputs to posterior parietal cortex (areas 5 and 7) 2) Prefrontal and parietal cortex is where decisions are taken (such as which actions/movements to take and their likely outcome) 3) Axons from both converge on area 6, where signals encoding desirected actions are converted into how to carry this out

Question 64

What Broddman areas are associated with the posterior parietal cortex?

Answer 64

Areas 5 and 7

Question 65

For movement, do the neurons in are 6 or area 4 fire first?

Answer 65

Area 6 fire before area 4, because area 4 is for "doing it" by activating neurons of the CST and RST

Question 66

Explain the process of neurons in the PMA (area 6) firing before movement?

Answer 66

1) Getting ready, few action potentials from PMA neurons 2) Get set, big increase in PMA action potentials 3) Go, PMA firing continues through actions, neurons in premotor area (PMA) fire action potentials one second before a movement occurs

Question 67

How long is between the premotor area (PMA) firing an action potentials and a movement occuring?

Answer 67

1 second

Question 68

What tells us that movement plans are rehearsed mentally?

Answer 68

Specific neurons in area 6 fire when movement is made and when movement is imagined