physio Flashcards
(from spinal cord, anterior horn) innervate
extrafusal muscle fibers and cause
contraction
alpha motor efferent
(descending fibers from brain)
innervate intrafusal muscle fibers
(muscle spindle) and responsible
for muscle tone (high gain)
gamma motor efferent
Only a few incoming signals from cord or brain terminate
directly on motor neurons
interneurons, alwyas inhibitory
stimulation of intrafusal muscle fibers causes 3 effects
increased tension in muscle spindle
increased sensitivity/gain
enhanced stretch relfex
where along the intrafusal muscle does the gamma neurons have effect, why?
Poles, no myofibrils present in the center
contract in response to stimulation of efferent alpha motor neuron originating in the anterior horn of the spinal cord; provide the force for the muscle contraction
extrafusal muscle fibers
which are bigger, intrafusal or extrafusal muscle fibers
extrafusal
where do the alpha motor efferents traveling to the extrafusal muscle fibers originate from
Anterior Horn of the spinal cord
Transmit sensory information to cord regarding muscle tension or rate of change in tension (interneuron)
Golgi Tendon
active muscle contraction stimulates the ____ ____ _____ and group __ afferert fibers. The group fibers then stimulate ______ which inhibit_________ and cause _______ of the muscle that was contracting
golgi tendon organs, Ib, interneurons, alpha motor neurons, relaxation
Golgi tendon reflex is: monosynaptic, disynaptic?
Disynaptic
how many synapse in a knee-jerk stretch reflex
monosynaptic
In the knee-jerk reflex, ____ motor neurons stimulate ______ muscle fibers to contract, thus _____ the muscle that was stretched, thus____
alpha, extrafusal, contracting, returning it to its regular length
beside the alpha motor neuron contracting the extensor, what other interaction is occuring with the flexors
synapse on interneurons which inhibit the alpha motor neurons to the flexors (antagonists)
UMN or LMN– inhibition of the gamma motor neurons, results in spastic paralysis
UMN
