Motor System - Overview & Cortical Influence Flashcards
Motor activity is generated and controlled through complex interactions of
- Brainstem tracts
- Frontal lobe, particularly primary motor cortex
- Cerebellum
- Basal ganglia
- Thalamus
complex pattern of muscle activation must be
planned and generated
Feedback occurs at all levels, but is primarily processed by
cerebellum
Peripheral motor control begins with?
the innervation of muscle by alpha motor neurons
alpha motor neuron innervates
one or more muscle fibers
size of a motor unit depends on what?
the number of muscle fibers it innervates
1 single motor neuron will innervate what?
1 fiber
Smaller motor neurons with lower thresholds (and lower contraction force) are what?
recruited first
larger motor neurons have what?
higher thresholds & generate more forces
Type I / S is what?
slow oxidative (SO)
- Small force
- slow twitch
- fatigue resistant
- Oxidative
- innervated by small diameter slow conducting axons
Type I / S = slow oxidative (SO)
postural control axons would be innervated by what kind of muscle fiber?
Type I / S = slow oxidative (SO)
Metabolic pathways are oxidative and anaerobic glycolytic would be innervated by what kind of muscle fiber?
Type IIa / FR = fast oxidative glycolytic (FOG)
gastrocnemius would be innervated by what kind of muscle fiber?
Type IIb / FF = fast glycolytic (FG)
- Intermediate force
- relatively fast contractile time
- generates larger tension
- intermediate to slow rate of fatigue
- innervated by large diameter rapidly conducting axons
Type IIa / FR = fast oxidative glycolytic (FOG)
Type IIa / FR is what?
fast oxidative glycolytic (FOG)
- rapidly contracting fibers
- rapidly fatigue
- white muscle
- contain large stores of glycogen
- high contraction force
- recruited later in the contraction pattern to recruit - - large forces
- large fibers supplied by large diameter axons
Type IIb / FF = fast glycolytic (FG)
Type IIb / FF is what?
fast glycolytic (FG)
primary peripheral sensory organs within a muscle to detect the speed and extent of muscle stretch
Muscle spindles or intrafusal muscles
a muscle contracts in direct response to its stretch
myotatic reflex
neuron used to adjust the tension or sensitivity of the muscle spindle as the muscle shortens
Gamma motor neuron
what type of muscle is important in the control of muscle tone (tension) in postural muscles mostly at an unconscious level
Gamma motor neuron
result in abnormal tone is a result in damage to what?
Gamma motor neuron
alpha-gamma coactivation
contraction of extrafusal muscle (on the outside [actually the muscle) which lengthens and contracts) while the intrafusal muscle (inside where the spindles are - length & speed of the stretch during actual contraction) or coactivation of alpha motor neuron and gamma motor neurons for accurate monitoring during motor movement