Term
| what is the basal ganglia pathway important for? |
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Definition
| selecting and initiating movements |
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Term
| The pathway involved in fine-tuning movements so that they are the right amplitude and speed includes which part of the brain? |
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Definition
|
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Term
| motor neurons of proximal muscles (such as the shoulder) are located more (medially/laterally) in the ventral horn |
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Definition
|
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Term
| motor neurons of distal muscles are located more (medially/laterally) in the ventral horn |
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Definition
|
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Term
| what are the motor neurons called that actually generate muscle contractions? |
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Definition
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Term
| what are smaller motor neurons which innervate muscle stretch receptors and can change the signaling from the stretch receptor? |
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Definition
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Term
T or F
A single motor neuron can innervate more than one muscle fiber |
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Definition
| True - A single motor neurons can innervate up to hundreds of individual muscle fibers. |
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Term
| the term for how many muscle fibers are innervated by one motor neuron |
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Definition
|
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Term
| what defines the "motor unit" |
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Definition
| the motor neuron and the muscle fibers that it contacts |
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Term
| when a motor neuron fires a single action potential, you can measure a single ______ |
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Definition
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Term
| a motor neuron firing several times in succession causes a muscle twitch to ______ |
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Definition
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Term
| quick enough firing of a motor neuron will cause the muscle to go from unfused _____ to fused _____ |
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Definition
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Term
| what are the 3 main types of motor unit? |
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Definition
slow
fast fatigue resistant
fast fatigable |
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Term
| which fibers have aerobic respiration, are myoglobin rich, have many mitochondria, have a dense blood supply, and are associated with small motor neurons? |
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Definition
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Term
| which fibers are anaerobic, have few mitochondria, produce lactic acid, and are associated with large motor neurons? |
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Definition
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Term
| which fibers can produce the most force? |
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Definition
|
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Term
| what is the motor unit size principle? |
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Definition
| You recruit the smallest motor neurons—the motor neurons with the smallest cell bodies first—which happen to innervate slow motor units, medium next, and the large motor neurons which go to the fast fatigable motor units last. |
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Term
| which receptor keeps track of muscle length? |
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Definition
| the muscle spindle or stretch receptor |
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Term
| what type of afferent fibers innervate the muscle spindle on the primary endings? |
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Definition
|
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Term
| what organ measures tension in the tendon? (measures how much force is being generated in the tendon) |
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Definition
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Term
| What type of afferent fibers innervate the muscle spindle on secondary endings? |
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Definition
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Term
| in the polar regions, the muscle spindle is innervated by ___neurons. These neurons control spindle CONTRACTION |
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Definition
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Term
| The stretch receptors are sensitive to what 2 things in general? They also signal the ____ of contraction |
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Definition
muscle stretch, position
also signal the speed of contraction |
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Term
| Holding out your arm and trying to keep it still when weight is suddenly added on is a monosynaptic reflex, so that when there is a muscle stretch, increased activity in the ______in increased activity in the motor units, which causes the muscles to contract |
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Definition
| Ia affrent neuron of the muscle spindle |
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Term
T or F
The Ia afferent also signals to an interneuron which will activate motor neurons in the antagonistic muscle. |
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Definition
False
the interneuron will inhibit the motor neurons in the antagonistic muscle |
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Term
| what is the role of the gamma motor neurons of the muscle spindle? |
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Definition
| gamma neurons basically keep the muscle spindle polar region stretched so that the central region can still signal |
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Term
T or F
In antagonistically paired muscles, if one muscle is contracting, then the other is always relaxing. |
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Definition
False
EX: holding arm out straight - both biceps and triceps are contracted |
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Term
| co-contraction of antagonistic pairing uses (involuntary/voluntary) control |
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Definition
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Term
| Increased activity in the Golgi tendon organ will result of inhibition of the motor neurons going to that muscle by the ____ neuron (this is a protective measure so as not to over contract) |
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Definition
| Ib inhibitory interneuron |
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Term
T or F
When arm wrestling/contracting muscle, at some point (a certain threshold) the signals from the Golgi tendon organs about tension in the tendons cause inhibition of the motor neurons so that the muscle stops contracting, and the muscle relaxes while the antagonist contracts. |
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Definition
| True - called the jack-knife response |
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Term
| what are the 2 reflexes that occur when you step on something sharp and pick your foot up very quickly without falling? |
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Definition
| flexion withdrawal reflex, crossed extensor reflex |
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Term
| what happens in the flexion withdrawal reflex? |
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Definition
| the extensor relaxes and the flexor contracts |
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Term
| what happens in the crossed extensor reflex? |
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Definition
| the opposite response from the flexion withdrawal reflex is induced in the contralateral leg. So the contralateral extensor contracts and the flexor relaxes. |
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