MSK 17 - Motor control 1

Question 1

what innervates the motor uni

Answer 1

alpha motor neurons

Question 2

what region of the brain is responsible for voluntary muscle contractions

Answer 2

primary motor cortex

Question 3

what is the path of the AP in the primary motor cortex

Answer 3

AP sent to upper motor neuron of primary motor cortex in pre central gyrus initiate movement

Question 4

where is the primary motor cortex located in relation to the gyrus

Answer 4

pre central gyrus

Question 5

what are the 3 classes of movement

Answer 5

voluntary

reflexes

rhythmic motor patterns

Question 6

what are voluntary movements

Answer 6

purposeful, goal directed movements initiated from within CNS

Question 7

what are reflex movements

Answer 7

somatic/automatic movements triggered in response to a specific sensory stimulus

Question 8

what are rhythmic motor pattern movements

what are 2 examples

Answer 8

initiation and termination is voluntary but actual movement is much more stereotyped

eg breathing, chewing

Question 9

what must be taken into account when considering the initiation and coordination of movement

Answer 9

the starting position of individual muscle fibres and body position

Question 10

what gives input about the starting position of individual muscle fibres and body position

Answer 10

proprioceptors

muscle receptors

Question 11

the forebrain is responsible for which of the 3 movement patterns

Answer 11

voluntary movements

Question 12

the spinal cord and brainstem is responsible for which of the 3 movement patterns

Answer 12

reflex movements and rhythmic motor patterns

Question 13

what are the 3 components of the brainstem which are involved in the motor system

Answer 13

thalamus

cerebellum

basal ganglia

Question 14

what does the thalamus do in the motor system

Answer 14

relay station for incoming motor and sensory signals

Question 15

what does the basal ganglia do in the motor system

Answer 15

approve or reject movement signals

Question 16

what does the cerebellum do in the motor system

Answer 16

detects and corrects motor errors

Question 17

where are motor neurons located

Answer 17

brain stem

spinal cord

Question 18

what are the 2 types of motor neurons

Answer 18

alpha and gamma motor neurons

Question 19

what do alpha motor neurons do

Answer 19

carry movement instructions from the brain and spinal cord to the muscles

Question 20

where do alpha motor neurons synapse

Answer 20

synapse on extrafusal muscle fibres

Question 21

the longest axons in the body belong to what neurons

Answer 21

alpha motor neurons

Question 22

where are gamma motor neurons located

Answer 22

in the same motor nucleus as alpha motor neurons

Question 23

where do gamma motor neurons synapse

Answer 23

synapse on intrafusal muscle fibres within muscle spindles

Question 24

what do muscle spindles do

Answer 24

send information about the position of muscle and muscle length

Question 25

where are alpha motor neurons located

Answer 25

in the anterior/ventral horns in the grey matter of spinal cord at every level

Question 26

what locations are alpha motor neurons concentrated in

Answer 26

in cervical and lumbosacral enlargments

Question 27

which nervous system controls movement

Answer 27

somatic motor pathway

Question 28

where are the cell bodies of somatic motor neurons located in

Answer 28

either in the ventral/anterior horn of spinal cord or the brain

Question 29

somatic motor neurons branch where relative to their target muscles

Answer 29

branch close to their target muscles

Question 30

each muscle fibre is innervated by how many motor neurons at how many neuromuscular junctions/end plates

Answer 30

only one motor neuron at one NMJ

Question 31

what are the 2 classifications of motor units

Answer 31

S (slow or type 1) type FF (fast/faitgable or Type 2 B) type

Question 32

when do the small motor units fire and what is their threshold like

Answer 32

fire first lower threshold

Question 33

the larger motor units are oxidative/glycolytic

Answer 33

glycolytic

Question 34

the larger motor units are oxidative/glycolytic

Answer 34

oxidative

Question 35

what are the 3 myosin heavy chain proteins in human skeletal muscles

Answer 35

MyHC 1, 2A and 2X.z

Question 36

what is the implication of having 3 myosin heavy chain proteins in human skeletal muscles

Answer 36

muscle fibre type composition exists along a continuum such that a single or multiple MyHC isoforms can be expressed the fast/slow muscle fibre types are determined by the MyHC isoforms and their properties

Question 37

what is the number of motor units for S type fibres relative to FF type fibres and vice versa

Answer 37

S type have many motor units FF type have few motor units

Question 38

what is the axon diameter for S type fibres relative to FF type fibres and vice versa

Answer 38

S type have smaller axon diameters FF type have larger axon diameters

Question 39

what is the number of terminals for S type fibres relative to FF type fibres and vice versa

Answer 39

S type have few terminals FF type have many terminals

Question 40

what is the tetanic tension for S type fibres relative to FF type fibres and vice versa

Answer 40

S type have small tetanic tension FF type have large tetanic tension

Question 41

what is the speed of contraction for S type fibres relative to FF type fibres and vice versa

Answer 41

S type slow speed FF type fast speed

Question 42

what is the fatigue level for S type fibres relative to FF type fibres and vice versa

Answer 42

S type have little/none fatigue and can maintain contractions at higher levels for much longer FF type have rapid fatigue

Question 43

what is the metabolism method for S type fibres relative to FF type fibres and vice versa

Answer 43

S type have aerobic metabolism FF type has anaerobic metabolism

Question 44

what is the myoglobin level for S type fibres relative to FF type fibres and vice versa

Answer 44

S type plentiful FF type scanty

Question 45

what is the glycogen level for S type fibres relative to FF type fibres and vice versa

Answer 45

S type little FF type much

Question 46

what is the mitochondria density for S type fibres relative to FF type fibres and vice versa

Answer 46

S type high density FF type low density

Question 47

what is the capillary supply level for S type fibres relative to FF type fibres and vice versa

Answer 47

S type high density FF type few

Question 48

what is the muscle fibre characteristics for S type fibres relative to FF type fibres and vice versa

Answer 48

S type small red FF type large pale

Question 49

what is the recruitment timeframe for S type fibres relative to FF type fibres and vice versa

Answer 49

S type early FF type late

Question 50

force produced by a muscle is increased in what 2 ways

Answer 50

increasing the frequency of APs in individual alpha motor neurons recruitment of additional motor units

Question 51

how does AP frequency relate to the muscle force

Answer 51

increase AP freq increases the muscle force

Question 52

describe small motor units in terms of excitability level, AP conduction and number and type of fibres excited

Answer 52

more excitable conduct APs more slowly excite fewer fibres that tend to be slow twitch type 1

Question 53

describe large motor units in terms of excitability level, AP conduction and number and type of fibres excited

Answer 53

less excitable conduct APs more rapidly excite many fibres that tend to be fast twitch type 2

Question 54

why is the conduction velocity of small diameter motor neurons low

Answer 54

smaller diameter means there is more resistance so conduction velocity decreases

Question 55

what do interneurons do

Answer 55

links input with the output within the spinal cord

Question 56

how many terminal branches do small diameter and large diameter motor neurons have relative to each other

Answer 56

large diameter motor neurons have many more terminal branches

Question 57

S type motor units are best suited for what load

Answer 57

for carrying sustained but small loads

Question 58

why do we need to exercise hard for the FF units

Answer 58

as they atrophy rapidly