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Flashcards in Motor Control #1 Deck (26)
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1
Q

Movement disorders are commonly caused by? And what are some examples of this?

A

Neurological disorders eg) myasthenia gravis, epilepsy, parkinsons

2
Q

What are the three types of movement?

A

1) Voluntary
2) Reflexes (somatic)
3) Rhythmic motor patterns

3
Q

What controls voluntary movement?

A

The forebrain, the cerebellum, thalamus, basal ganglia

4
Q

What controls Reflexes and rhythmic motor patterns

A

The spinal cord and brainstem

5
Q

What are rhythmic motor patterns?

A

breathing, locomotion, chewing. Semiautomatic movements that are inbetween reflex and will. We can control to a point.

6
Q

What are the two subcortical loops that impact our decision making?

A

CC > Basal ganglia > thalamus

CC > Brain stem > cerebellum > thalamus

7
Q

Where are the two places you’ll find motoneurons

A

Motor nuclei in the ventral horns of spinal cord
Motor nuclei in the brain stem (midbrain pons and medulla oblongata) this is done through cranial nerves sending axons to muscles

8
Q

how many cranial nerves actually send axons

A

9/12

9
Q

Two types of motoneurons, and what do they innervate?

A

alpha motoneurons, innervate extrafusal fibres (the most common muscle fibres)
Gamma motoneurons, innervate intrafusal muscle fibres. this controls the excitability of stretch receptors muscle spindle fibres

10
Q

Are Alpha and gamma motoneurons independent?

A

No, a and g motoneurons often have co-activation

11
Q

Sir John Eccles

A

studied and characterised motoneurons, lectured in otago, the 1st to measure RMP, AP, synaptic potential.

12
Q

What was sir John Eccles technique?

A

Used a glass microelectrode. If you add dye you can see the morphology of nerve cells.

13
Q

What are the components of motor units

A

a) Cell body of an a-MN
b) axon
c) all neuromuscular junctions (synapses) formed by a single motoneuron
d) all muscle fibres (extrafusal muscle fibres) innervated by a single motoneuron

14
Q

what is the innervation ratio?

A

the amount of muscle fibres a MN can innervate (between 5 to 20,000).

15
Q

Motor unit types

A
FF type 11B - fast fatigable
S type (type 1)  - slow twitch
16
Q

FF type 11B

A

Glycolytic, short twitch time (20ms), large, powerful, a few, rapidly fatigue

17
Q

S type (type 1)

A

oxidative, slow (50ms+), small, weak, there are many and they are slow to fatigue

18
Q

What makes S-type a good choice over FF type

A

There are many, and they are slow to fatigue, unlike FF type

19
Q

What are S type and FF type useful for?

A

S type- continuous, weak contractions

FF type - brief, strong contractions

20
Q

What is the size principle of motor units?

A

S type recruited first, FF type are recruited only at highlevels of muscle force

21
Q

What are the physiological consequences of the size principle?

A

S type MU fire almost always
S type are for sustained, small loads
Weak contractions are graded better then strong
Atrophy of FF will occur without excercise

22
Q

What motor neurons are activated during REM sleep?

A

eyes, respiratory, sphinters

23
Q

How are muscles ‘slaves’ to nerves?

A

The properties, types of contractions are changed with cross innervation! This is done with experiment between soleus and gastrocnemius

24
Q

What do gamma MN innervate and what does this do?

A

They innervate the periphery of intrafusal fibres (muscle spindles) where there are contractile elements. This enhances the ability of the spindle to stretch

25
Q

What do gamma MN sense?

A

the changes in muscle length

26
Q

Whats the difference between somatic and autonomic neurons

A

Somatic go directly to muscles, whereas autonomic use parasympathetic/sympathetic ganglia as ‘switches’