✅Voluntary Motor Control Flashcards
What is a motor unit made up of?
a motor neuron and the skeletal muscle fibers innervated by that motor neuron’s axonal terminals.
Why do groups of motor units work together?
To coordinate the contractions of a single muscle.
What are all the motor units in a muscle called?
A motor pool
What are All muscle fibres are innervated by?
1 motoneurone
What does each moroneurone innervate?
Many muscle fibres within the same muscle
How many types of motor units are there?
3
What are the 3 types of motor units related to?
The size of the motoneurone, the number of muscle fibres innervated and the mechanical properties of those fibres
Muscle fibers of different motor units are intermingled. True or False?
True
What happens as a result of the muscle fibres being intermingled?
The forces applied to the tendon remain roughly balanced regarding which motor units are stimulated.
What are muscle properties determined by?
The proportion and type of motor units they contain.
What are the two types of muscles?
Fast and Slow
What are fast muscles?
Pale muscle fibres, when simulated, they contract rapidly
What are slow muscles?
Red muscle fibres, when simulated, they contract slowly.
How are differences reflected?
in contractile and biochemical characteristics of muscle fibres in different motor units
What is type 1 muscle fibre?
Long distance, slow twitch , low fatigue rate (mo Farrah)
What is type 2A muscle fibre?
400/800m, fast twitch oxidative, medium fatigue rate/
What is type 2B muscle fibre?
Short sprint, fast twitch glycolytic, high fatigue rate. (Usain Bolt)
What is recruitment (with regards to motor units)
Multiple motor unit summation
What happens in a whole muscle or group of muscles? (Motor unit recruitment)
smooth motion and increasing tension are produced by slowly increasing the size or number of motor units stimulated.
What is the size principle?
Under normal circumstances, MU are recruited to movement before larger ones
When is maximum tension achieved?
When all motor units reach tetanus, can be sustained only a very short time
Describe white muscles
- mostly fast fibres
- Pale ( chicken breast)
Describe red muscles
- mostly slow fibres
- dark (chicken legs)
What are most human muscles made up of?
Mixed fibres:
- fast
- slow
- intermediate
Describe 5 features of fast fibres. (Usain Bolt)
• Contract very quickly
• Have larger diameter, large glycogen reserves,
few mitochondria
• Poor oxidative enzyme capacity
• High anaerobic enzyme activity
• Have strong contractions, fatigue quickly
Describe 6 features of slow fibres (Mo Farrah)
• Are slow to contract, slow to fatigue
• Have small diameter, small mitochondria
• Have high oxygen supply
• Large oxidative enzyme activity
• Low anaerobic enzyme activity
• Contain myoglobin (red pigment, binds oxygen)
Describe 5 features of intermediate fibres.
• Are mid-sized
• Have low myoglobin
• Have more capillaries than faster fibres, slower
to fatigue
• Intermediate oxidative capacity
• High anaerobic enzyme activity
What is sarcopenia?
Age related muscle atrophy
What happens with age?
There is a loss of larger motor units
Fast and high force movements are difficult for what age group?
Elderly
What does the cerebral cortex do with regards to movement?
Complex and skilled motor acts.
What does the spinal cord do with regards to movement?
Postural,protective reflexes, locomotion
What does the brain stem do with regards to movement?
Breathing, chewing, swallowing and eye movement.
What does the basal ganglia do with regards to movement?
Initiation of motor behaviour
What do the hypothalamus do with regards to movement?
Eating/drinking
What are fine motor skills?
Speech, hand and finger control.
What are the three stages of the basic functions of descending tracts?
- Cortico- and Rubrospinal
- Reticulospinal
- Vestibulospinal
What are the two steps of the Cortico stage?
- Transmission of commands for skilled movements.
2. Corrections of motor patterns generated by the spinal cord.
What are the two stages of the reticulospinal stage?
- Activation of spinal motor programs for stepping and other stereotypic movements
- Control of upright body posture.
What is the step at the vestibulospinal stage?
Generation of tonic activity in antigravity muscles
What is the convergent information flow in motor planning?
Sensory periphery/eye -> input from muscles, skin and joints/ location and movement of objects-> somatic afferent pathways/Visual afferent pathway -> Primary Somatic Sensory Cortex/ Primary Visual Cortex -> SENSORY SYSTEM -> MOTOR SYSTEM-> Primary Motor Cortex -> Direct system/ Indirect System -> spinal cord/ spinal cord -> Muscles of hand and arms/ reflexes and postural adjustments.
What happens when we learn a movement?
we first execute it very slowly because it cannot be adequately programmed.
What happens because a movement cannot be adequately programmed?
Instead, it is performed largely by intense cerebral concentration as well as with the constant updating via the cerebellum.
What happens With practice and the consequent motor learning?
a greater amount of the movement can be programmed and the movement can be executed more rapidly.
What happens with very rapid movements?
we rely entirely on pre-programming because there is no time for on-target correction once the movement has begun.
What do we have to envisage when carrying out skilled movement?
there is an immense integration of neuronal activities in interacting dynamic loops.
Where are mirror neurons found?
in the premotor cortex
When do they discharge?
Both when making a movement, or when observing a movement being performed by another.
What is voluntary movement?
It needs sensory feedback
It helps brain visualise movement
It helps brain plan how to sequence a movement (motor programme)
Helps update and automate trained actions.
