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52 Cards in this Set
- Front
- Back
What are the four motor systems?
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1) Higher centers
2) Brainstem 3) Spinal Cord 4) Motor unit |
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What is the function of the motor unit in terms of motor activity?
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muscle contraction
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What is the function of the spinal cord in terms of motor activity?
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spinal reflexes
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What is the function of the brainstem in terms of motor activity?
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control of posture
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What is the function of the higher centers in terms of motor activity?
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voluntary movement planning and execution
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What structures are considered part of the upper motor neurons? (4)
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1)motor cortex
2)basal ganglia 3)cerebellum 4)brainstem |
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What structures are considered part of the lower motor neurons?
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1) spinal reflexes
2) motor neurons |
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What structures are the common final pathway?
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motor unit
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In the spinal cord what is the topigraphical distribution for the proximal/axial muscles?
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medial
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In the spinal cord what is the topigraphical distribution for the distal/extremity muscles?
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lateral
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In the spinal cord what is the topographical distribution of the flexor muscles?
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dorsal
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In the spinal cord what is the topographical distribution of the extensor muscles?
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ventral
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What are the components of the motor unit?
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1) single motor neuron
2) motor neuron axon fibers 3) muscle fibers that the motor neuron innervates |
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hat is the motor neuron pool?
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group of motor neurons that innervate muscle fibers within th same muscle
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What is the innervation ratio?
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muscle fibers per neuron
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Which muscles have the highest innervation ratio?
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large motor neurons
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Which muscles have the lowest innervation ratio?
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small motor neurons
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What are the three different types of motor units?
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1) slow motor units
2) fast fatigue resistant motor units 3) fast fatigable motor units |
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What is the size principle of recruitment order?
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1) slow motor units
2) fast fatigue resistant motor units 3) fast fatigable motor units |
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Are smaller or larger motor units more likely to fire first or last?
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small motor units are more likely to fire first
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Which of the motor unit sizes has a lower threshold smaller or bigger motor units?
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smaller
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Which of the motor units generates the most amount of force, smaller or larger?
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larger
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What type of neuron is associated with an intrafusal muscle fiber/spindle?
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alpha motor neuron
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What type of neuron is associated with a nuclear chain fiber?
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gamma motor neuron
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What type of interfusal fiber neuron is associated with a dynamic response?
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group 1a
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What type of interfusal neuron is associated with a static response?
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group ii
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What is the muscle stretch reflex?
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1) stretch on muscle spindle
2) Ia afferents bring in the signal in the spinal cord 3) alpha motor neurons act on muscle |
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What is recipical innervation?
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antagonist muscle is inhibited by an interneuron
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is the stretch reflex monosynaptic?
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yes
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What is the effect of stretch or contraction on the Ia afferents?
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stretch - activates them
contraction - inhibits them so you will stop contracting |
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What is the Jendrassik manuever?
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you increase gamma stimulation to the muscle this increases sensitivity of muscle spindle at different lengths
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What is the role of gamma motor neurons?
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you get a sensitivity of muscle at different lengths like even while you are contracted
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What is the principle of coactivation?
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Alpha motor neuron stimulation causes gamma motor neuron costimulation which allows muscle spindles to maintain sensitivity during muscle contraction
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What is the best activator of the golgi tendon orgal?
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active contraction of extrafusal muscle fibers
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What is the different intrafusal vs extrafusal for which type of sensory receptor in muscle? what about type of motor neuron fiber?
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intrafusal - nuclear chain and bag/muscle spindle (gamma)
extrafusal - golgi tendon organ (alpha) |
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Does the golgi tendon organ respond well to passive stretch? What does?
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no, the extrafusal/golgi tendon organ does not respond. it responds best to active contraction. well but the intrafusal/spindle afferent does
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Does the muscle spindle respond well to active stretch? what does?
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intrafusal organ responds well to passive stretch
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What is the Golgi Tendon/inverse motatic reflex?
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1) Golgi tendon organ senses force
2) Ib afferents relay that force to spinal cord 3) inhibition of homonymous (same muscle fiber) by interneurons 4) activation of antagonists by interneurons |
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Is the golgi tendon/inverse myotatic or the myotactic disynaptic? Which one is monosynaptic which one is disynaptic?
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golgi tendon - disynpatic
muscle spindle - monosynaptic |
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Which sensory fibers are associated with the Golgi tendon organ?
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1b
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What stimuli is the flexor withdrawal reflex associated with?
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touch, temperature, pain
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What is the flexor withdrawal reflex?
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1) touch, temperature and pain afferents go to interneurons in spinal cord
2) ipsilateral flexion is activated 3) ipsilateral extension is inhibited |
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What is crossed extension in the flexor-withdrawal reflex?
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contralateral extension is activated
contralateral flexion is inhibited |
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What is the after discharge in the flexor withdrawal reflex?
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residual ipsilateral extensor inhibition and flexor activation so you are in that position for a bit longer
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What are the sensory fibers that do the afferents of the flexor withdrawl reflex?
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1)group II
2) group III (a delta) 3) group IV/C fibers |
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What is the purpose of the crossed extension?
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ipsilateral flexion/withdrawal and contralateral extension to help you maintain balance
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What is the stimulus/sensory organ, afferent, synapse and response for the stretch reflex?
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Stimulus- Muscle Spindle
Afferent - Ia Synapse - One/Monosynaptic Response- Contraction |
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What is the stimulus/sensory organ, afferent synapse and response for the golgi tendon reflex?
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Stimulus- Golgi tendon
afferent - Ib Synapses- Disynaptic Response - Relaxation |
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What is the stimulus/sensory organ, afferent synapse and response for the flexor withdrawal reflex?
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stimulus - touch, temperature and pain
afferent - II, III, IV synapse - polysynaptic response - ipsilateral flexion |
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What is lower motor neuron syndrome?
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1)paralysis/loss of movement or weakness (paresis)
2) loss of reflexes 3) loss of muscle tone 4) muscle atrophy 5) fasiculations (spontaenous muscle twitches) |
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What is the cause of Amyotrophic lateral sclerosis (ALS)?
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1)slow degeneration of motor neurons in spinal cord (LMNs) and motor cortex (UMNs)
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What are the symptoms of ALS?
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1) progressive weakness, atrophy and muscle twitching
2) sensory function is unaffected 3)mental status/intellect remains intact |