Slide 1

Question 1

Pathway of motor neurons

Answer 1

• brain -> spinal cord -> muscles

- descending neural pathway

Question 2

Common misconception about sensorimotor control

Answer 2

-misconception: sensorimotor control is just about muscle control

Question 3

What does movement primarily depend on?

Answer 3

• overall plan

- constant sensory feedback

Question 4

Where is the motor cortex found in relation to the somatosensory cortex?

Answer 4

-right next to each other

Question 5

Where is the motor cortex located?

Answer 5

frontal lobe

Question 6

Where is the primary somatosensory cortex located?

Answer 6

• postcentral gyrus

- in parietal lobe

Question 7

Which cortex is responsible for sensorimotor input/outor?

Answer 7

input: sensory cortex
output: motor cortex

Question 8

Which side of the body does the left side of the motor cortex control?

Answer 8

right side

Question 9

Which side does the left hemisphere of the sensory cortex receive input from?

Answer 9

right side of the body

Question 10

What are the 3 categories of movement of the sensorimotor system

Answer 10

1) Voluntary movement
2) Reflexes
3) Rhythmic motor patterns

Question 11

Describe voluntary movements

Answer 11

• under control

- eg. snapping

Question 12

Describe reflexes

Answer 12

• automatic
• involuntary
• stereotypes
• rapid
• eg. knee jerk reflex

Question 13

Describe rhythmic motor patterns

Answer 13

• repeated patterns of movement
• mediated by central pattern generators
• eg. respiration

Question 14

4 Principles of sensorimotor function

Answer 14

• Hierarchical Organization
• Parallel Processing
• Sensory feedback essential
• Motor system learns

Question 15

Describe hierarchical organization of the sensorimotor function

Answer 15

-Association cortex -> secondary motor cortex -> primary motor cortex -> brain stem motor nuclei -> spinal motor circuits

• complex processing at the top (association cortex)
• simple processing at the bottom (muscles)

Question 16

Describe parallel processing in sensorimotor system

Answer 16

signals flow between levels over multiple paths

Question 17

Why is sensory feedback essential in the sensorimotor system?

Answer 17

motor output is guided by sensory input

Question 18

Define motor learning

Answer 18

• process by which motor programs are created and modified

- learned, fixed sequence of movements

Question 19

Give an example of motor learning

Answer 19

playing piano

Question 20

What is a motor unit?

Answer 20

• a single motor neuron
• and the muscles in innervates
• all fibers contract when the motor neurons fire

Question 21

What are flexors?

Answer 21

• example of skeletal muscle
• muscles contracts
• and bends a joint

Question 22

Give an example of a flexor

Answer 22

bicep

Question 23

What are extensors?

Answer 23

• example of a skeletal muscles
• muscle contacts
• and straightens a joint

Question 24

Give an example of an extensory

Answer 24

tricep

Question 25

What are antagonistic muscles?

Answer 25

-2 sets of muscles which cause opposite movements

Question 26

Given an example of antagonistic muscles

Answer 26

biceps and triceps

Question 27

What are synergistic muscles?

Answer 27

-2 sets of muscles which cause the same movement when they contract

Question 28

Give an example of synergistic muscles

Answer 28

-biceps and brachioradialis

Question 29

What are skeletal muscles made up of?

Answer 29

myocytes

Question 30

What are myoctyes?

Answer 30

muscle fibers

Question 31

What is a motor pool?

Answer 31

All motor units controlling the same muscle

Question 32

What is movement precision based on?

Answer 32

innervation ratio

Question 33

What is innervation ratio?

Answer 33

ration of motor neurons to muscle fibers

Question 34

What does a low innervation ratio result in?

Answer 34

precise movements | -eg. hand/eyes

Question 35

What does a high innervation ratio result in?

Answer 35

less-precise movements

Question 36

What happens at the neuromuscular junction of a motor unit?

Answer 36

- motor neuron - connects to - motor end plate of muscle fiber - action potential in motor neuron releases acetycholine - causes muscles to contract

Question 37

What chemical is released to cause muscles to contract?

Answer 37

acetycholine

Question 38

2 main components of a motor unit

Answer 38

- muscles | - neuromuscular junction

Question 39

What are proprioceptors?

Answer 39

- somatosensory receptors - that transmit info - regarding the position or movement of a body part - eg. muscle or joint

Question 40

What are the two proprioceptors in the sensorimotor

Answer 40

- Golgi tendon organs | - Muscle spindles

Question 41

Where are golgi tendon organs embedded?

Answer 41

embedded in tendons

Question 42

What do golgi tendon organs respond to?

Answer 42

-changes in muscle tension

Question 43

What is the function of golgi tendon organs?

Answer 43

protect muscles from being overstretched | causes muscles to relax

Question 44

Process of golgi tendon function

Answer 44

- golgi tendon organs detect tension - send action potential to spinal cord - activate motor neurons - cause muscles to relax

Question 45

Where are muscle spindles embedded?

Answer 45

in muscle tissue

Question 46

What do muscle spindles respond to?

Answer 46

changes in muscle length

Question 47

What is the function of muscle spindles

Answer 47

cause contraction

Question 48

mechanics of muscle spindles

Answer 48

- has its own intrafusal muscle | - innervated by its own intrafusal motor neurons

Question 49

Role if intrafusal motor neurons

Answer 49

- adjust length of intrafusal muscles | - which maintains an appropriate degree of mucsle tension

Question 50

Give 2 types of reflex

Answer 50

- stretch reflex | - withdrawal reflex

Question 51

What is another name for the stretch reflex?

Answer 51

patellar tendon reflex

Question 52

When does the stretch reflex occur?

Answer 52

when length of a muscle issuddenly extended

Question 53

True or false: stretch relexes are monosynaptic

Answer 53

true

Question 54

What is monosynaptic?

Answer 54

only involves 1 synapse

Question 55

Process of a stretch reflex

Answer 55

- afferent neuron brings sensory signal into spinal cord - efferent neuron sends motor command - muscle contracts

Question 56

When does the withdrawal reflex occur?

Answer 56

occurs when one touches something painful

Question 57

How is the withdrawal reflex different from the stretch reflex

Answer 57

- not monosynaptic | - involves interneurons

Question 58

Reciprocal innervation

Answer 58

- some neurons excite excitatory interneurons - other neurons excite inhibitory interneurons - excitatory interneuron causes contraction of bicep - inhibitory interneuron causes relaxation of tricep

Question 59

Which interneuron causes the contraction of a bicep?

Answer 59

excitatory

Question 60

Which interneuron causes the relaxation of triceps?

Answer 60

inhibitory

Question 61

What is recurrent collateral inhibition?

Answer 61

- feedback loop - through Renshaw cells - gives muscle fibres a rest - after every contraction

Question 62

What is the purpose of recurrent collateral inhibition?

Answer 62

- purpose is to distribute work - between different motor units - of a muscle's motor pool

Question 63

Steps of recurrent collateral inhibition

Answer 63

- motor neuron branches (collateral axon) - interneuron - inhibits that motor neuron

Question 64

Where is the primary motor cortex located?

Answer 64

- anterior to the central fissure | - along the precentral gyrus

Question 65

How is the primary motor cortex organized

Answer 65

somatotopic organization

Question 66

Penfields studies

Answer 66

- mapping the functions of various regions of the brain | - if a part of a brain is stimulated, which body part will it affect?

Question 67

True or false: primary motor cortex is primarily contralateral ie. right side of brain controls left side of body

Answer 67

true

Question 68

What is the major function of the primary motor cortex?

Answer 68

initiating body movements

Question 69

Where does the primary motor cortex receive input from?

Answer 69

- secondary motor areas - prefrontal cortex - primary somatosensory cortex

Question 70

Properties of primary motor cortex neurons

Answer 70

-code for direction in which limb is meant to travel -individual neurons have diff directional preferences -fire in relation to target location -

Question 71

What are the effects of damage to the primary motor cortex

Answer 71

- Mostly contralateral defecitys - causes asterognosia - response weakness (speed, accuracy, strength) - difficulty in moving body parts

Question 72

What is the effect of damage to s2/association cortex?

Answer 72

- somatosensory agnosia | - asterognosia

Question 73

What is asterognosia?

Answer 73

inability to recognize objects by touch

Question 74

True or false: damage to primary motor cortex can cause paralysis

Answer 74

false