Neurophysiology - Motor System

Term

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Reflex Arc

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Terms in this set (21)

basic unit of integrated neural activity of motor action

Mono-synaptic Reflex

simplest reflex arc; single synapse b/w afferent and efferent neurons; built for speed

aka intrafusal fibers-functions to maintain muscle length (sense organ of mono-synaptic reflex); signals muscle's length and rate of change in length (stretch leads to contraction of muscle); PARALLEL to muscle

Intrafusal Fibers

2-10 muscle fibers enclosed in CT capsule
2 types: 1. nuclear bag (dynamic response) 2. nuclear chain (static response)

Extrafusal Fibers

regular contractile units of the muscle

1a Afferent Fiber

sensory fiber of muscle spindle that synapses directly on alpha motor neurons supplying extrafusal fibers of same muscle; firing rate of this is proportional to stretch of intrafusal fiber

α Motor Neuron

motor neuron supplying motor function to extrafusal fibers

Gamma Nerve Fiber

small, efferent motor nerve supply to muscle spindle

Gamma Efferent Discharge

shortens intrafusal fibers and stretches muscle spindle->increases spindle discharge->excitation of α motor neurons->reflex contraction of muscle; leads to varying of muscle spindle sensitivity

Poly-synaptic Reflex

reflex arc in which one or more interneurons are interposed b/w afferent and efferent neurons; enables complex movements (excitation and inhibition of different muscles)
e.g. inverse stretch reflex, withdrawal reflex, reciprocal innervation, cross extensor reflex