Control of movement Flashcards
(32 cards)
3 types of physiological movement
Voluntary
Reflex
Rhythmic motor pattern
Voluntary motor movements are controlled by:
The forebrain
Reflexes and rhythmic motor patterns are controlled by:
The spinal cord and brainstem
Alpha motoneurons
Innervate extrafusal muscle fibres
Responsible for force generation
Gamma motoneurons
Control excitability of stretch receptors in muscle spindles
Innervate intrafusal muscle fibres
4 components of the motor unit
1) cell body
2) axon
3) synapses
4) muscle fibres
FF type
Fast twitch, fatiguable
Type 2b fibres
S type
Slow twitch
Type 1 fibres
The type of motor units recruited first are:
S type
FF type units are only recruited:
At high levels of muscle force
Alpha motoneurons are the final common path for:
1) Descending tracts
2) Spinal interneurons
3) Propriospinal neurons
Main receptors which control movement
Muscle spindles
Golgi tendon organs
Nociceptive receptors
Joint receptors
Muscle spindles monitor:
Muscle length and speed of length change
Golgi tendon organs monitor:
Muscle tension
Nociceptive receptors monitor:
Pain
Join receptors monitor:
Position
Five elements of spinal reflexes
Receptors Afferent fibres Central synaptic relay Efferent fibres Effectors
Only monosynaptic reflex in the body
Stretch reflex
Receptor of stretch reflex
Mechanoreceptors
Afferents of stretch reflex
Type Ia afferents
Synaptic relay of stretch reflex
Glutamatergic excitatory synapses on alpha motoneurons
Efferents of stretch reflex
Axons of alpha motoneurons
Effectors of stretch reflex
Synergistic muscle
Latency of the knee jerk reflex
25-30 ms
