Term
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Definition
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Term
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Definition
| alpha and gamma motor neurons |
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Term
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Definition
| small encapsulated structures innervated by Ib afferent, in series with muscle because stretches with muscle, detects muscle tension. cannot be activated by just pulling on the tendon, works best when muscle is pulled in both directions (like when moving a load). responds to contraction of a single motor unit |
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Term
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Definition
| innervated by Ia afferents, consist of intrafusal muscle fibers in a capsule, different from extrafusal fibers so said to be in parallel with muscle, senses stretch |
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Term
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Definition
| middle of intrafusal fibers where the terminals of the afferent fibers are because there arent' many contractile elements |
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Term
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Definition
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Term
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Definition
| rate at which muscle length is changing |
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Term
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Definition
| type of intrafusal muscle fiber, - static aspects of stretch. has Ia and II fibers innervating it |
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Term
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Definition
| dynamic aspects of stretch...innervated by Ia |
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Term
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Definition
| static aspects of stretch - innervated by Ia and II |
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Term
| primary or annulospiral endings |
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Definition
| Ia afferent fiber in a spindle that has input on all fibers |
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Term
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Definition
| II that only iinnervate nuclear chain and bag-2 fibers |
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Term
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Definition
| summated synaptic depolarizations that cause graded contraction of intrafusal fibers |
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Term
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Definition
| motor innervation of intrafusal fibers - causes contractile poles of intrafusal fibers to shorten to bias the spindle and change its sensitivity and transducing properties |
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Term
| dynamic gamma motor neurons |
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Definition
| innervate nuclear bag 1 fiber. enhances the response of the motor neurons to rate of stretch. |
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Term
| static gamma motor neurons |
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Definition
| innervate bag-2 fibers and nuclear chain fibers. enhances the response of the spindle to maintained stretch. |
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Term
| alpha-gamma co-activation |
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Definition
| allows the muscle spindle to "stay on the air" |
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Term
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Definition
| opposes lengthening of a muscle when a load is added. antigravity! |
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Term
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Definition
| stretch of a given muscle (the agonist) excites primary endings on spindles through Ia axons, which synapse on alpha motor neurons and inhibit the opposing muscles (antagonist) |
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Term
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Definition
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Term
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Definition
| increased reflex excitability of the stretch reflex |
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Term
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Definition
| hyperreflexia + hypertonia |
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Term
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Definition
| paralysis/inability to move, because of spasticity |
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Term
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Definition
| caused by damage to the motor nerves or muscles themselves |
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