Lecture 1

Question 1

Why is the motor control not intuitive?

Answer 1

Because we have to think about what muscle is moving rather than the goal of the movement.

Question 2

What is the 2 overall function of motor system?

Answer 2

-coordination and posture

Question 3

What are the 5 mechanical basis of muscle movement?

Answer 3

1) Most movement occurs at the joints were two bones meet
2) Muscles contract and pull
3) Muscles around each point have to be agonists and antagonists
4) Muscle working due to changes in their lengths and join angles

Question 4

What is the difference between flex and extend?

Answer 4

Flexion is decreasing joing angle and extension is the opposite.

The agonist is the muscle acting and the antagonist is the muscle doing the opposite
Synergists are muscles working together

Question 5

What is posture?

Answer 5

Its the resting force of gravity
Anti gravity are extensors and their antagonists are flexors.

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Question 6

What is postural fixation?

Answer 6

Elimination of unwanted movement. So it stabalizes the overal posture without using muscles that are unnecessary

Question 7

What are the 4 main porperties of a muscle action?

Answer 7

Force, resistance to fatigue, speed of contraction and fineness of control

First three are from muscle structure and the fineness of control is due to innervation and structure of muscle

Question 8

What is the 2 different muscle fibers?

Answer 8

-Fast twitch and slow twitch muscles

Question 9

What is fast twich muscle?

Answer 9

• FF fibers which is faster, fatiguable but more force

- FR: faster, more resistant to fatigue and more force.

Question 10

What is slow twitch muscle?

Answer 10

S: Fibers. least force, slow contration time and more resistant to fatigue.

Question 11

Can training change muscle type or amount of muscle fibers?

Answer 11

FALSE

Question 12

So is each muscle a specific kind of fibers?

Answer 12

NOPE. each muscle is a mixture of the 3 fibers.
different %s of each fiber vary on the action of the muscles

Compositions of each muscle also vary between individuals.

Question 13

What is the composition of the efferent fibers of muscles?

Answer 13

1) alpha motor neuron
2) cell bodies in ventral horn axons leave via ventral roots
3) axons have very large axons, myelinated alpha fibers
4) 12-20 uM diameter which gives a speed of conduction of 70-120 m/s
Each AXON innervates 2-1000 fibers

Question 14

What is a motor neuron pool>

Answer 14

All motor neurons innervating one muscle distributed over different cord segments

Question 15

What do motor neurons release?

Answer 15

Motor neurons release trophic factors which are crucial for muscle health

Question 16

What happens if MN dies?

Answer 16

MUSLCE ATROPHY which is what happens with ALS due to lack of the trophic factors.

Question 17

All types of fibers in a motor unit are the same

Answer 17

that means all fibers of a single Motor mass have FF or has S muscle types

Question 18

SO whats the summary?

Answer 18

Larger MN= more innervated fibers= Larger muscle unit= more force produced, quicker response and sooner fatigue

Question 19

How does the motor uint size differ between muscles?

Answer 19

• The fine control has smaller average motor unit and the opposite is true for force and speed muscles

Question 20

What is the size principle?

Answer 20

When muscle wants to acomplish a movement it first activates the smallest and then up to the last and vice versa

Which means S motor fibers are more in use

Question 21

What kind of feedback of muscle to CNS?

Answer 21

1) is the GTO which is golgi tendon organ. which is a receptor of muscle force.
2) Muscle length and their receptors is the muscle spindle
- -Static info means the muscle is not working (same length)
- -Dynamic info is the rate of change in length

Question 22

Whats the difference between fibers of muscle fibers and muscle spindle

Answer 22

Muscle spindle has intrafusal fibers vs extrafusal fibers in muscle fibers/

-Muscle spindles contain a CT sheat with intrafusal fibers

Question 23

Whats the difference between intrafusal fibers an dextra fusal fibers?

Answer 23

• Intrafusal fibers have both contactile and non contractile poles
• Intrafusal is also multinucleated
• intrausal have 2 types of different structures m innervation and info. Bag vs chain

Question 24

What is the sensory information of spindle?

Answer 24

Group A fibers which is faster and larger in diameters.
–Group A innervates every intrafusal fibers
Form primary or annulospiral endings.
Convery into both dynamic and static info

Question 25

What is the function of group II muscle fibers?

Answer 25

innervate only seconadry chain fibers
-seconadry flower spray ending
convery static force only