Motor control

Question 1

What connects muscle to bone?

Answer 1

Tendon

Question 2

What does motor unit contain?

Answer 2

Alpha motor neurons and all extrafusal skeletal muscle fibres it innervates

Question 3

Function of upper motor neuron?
Cell body?

Answer 3

Innervate muscle
Cell body originates in cerebral cortex or brainstem
Terminates within brainstem or spinal cord
All UMNs exert effects via LMNs

Question 4

What neurotransmitter normally involved in upper motor neurons?

Answer 4

Glutamate

Question 5

What does damage to UPM cause?

Answer 5

Weakness/paralysis of movement for group of muscles it innervates

Question 6

Give 3 signs of UMN damage?

Answer 6

Hypertonia- toned due to muscle loss
Spasticity
Stroke (internal capsule)

Question 7

Function of lower motor neuron?

Answer 7

Connects the UMN and skeletal muscle it innervates

Question 8

Can a single LMN innervate one or several muscle fibres?

Answer 8

Single LMN can innervate several muscle fibres
Single muscle fibres is innervated by only one LMN

Question 9

What are two types of LMN?

Answer 9

α-Motor Neurons
γ-Motor Neurons

Question 10

Function of α-Motor Neurons?

Answer 10

Cause contraction of muscle fibres
Voluntary
Stretch response

Question 11

Function y-motor neurons?

Answer 11

Regulate muscle tone
Maintain nonconscious proprioception

Question 12

Signs of LMN damage?

Answer 12

Hypotonia
Muscle atrophy

Question 13

Define muscle tone?

Answer 13

Degree of contraction of muscle or proportion of motor units that are active at any one time

Question 14

Characteristics of muscle in high tone?

Answer 14

Firm/rigid

Question 15

Characteristics muscle in low tone?

Answer 15

Soft

Question 16

What type motor neuron is responsible forstretch?

Answer 16

Alpha motor neuron

Question 17

At neuromuscular junction what neurotransmitter do axon terminals contain?

Answer 17

Ach in vesicle

Question 18

What is the junction of an axon terminal with motor end plate called?

Answer 18

Neuromuscular junction

Question 19

Where is action potential propagated?

Answer 19

Surface muscle fibre
Into T tubules
Spread throughout muscle

Question 20

Explain how endplate potential is generated?

Answer 20

1) Action potential arrives at axon terminal and depolarises plasma membrane
2) Voltage-gated Ca2+ channels open and
3) Calcium ions diffuse into axon terminal
4) Calcium binds to proteins- allow ACh vesicles to fuse with the neuron plasma membrane
5) ACh diffuses to motor end plate
6) ACh binds to cholinergic nicotinic receptors
7) Opens ion channel in receptor protein
8) More Na+ moving in than K+ moving out
9) EPP is produced.

Question 21

Is end plate bigger than normal potentials?

Answer 21

Yes- big surface

Question 22

Are neuromuscular junctions excitatory or inhibitory?

Answer 22

Excitatory

Question 23

Answer 23