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extrapyramiddal system consists of
- all motor tracts from brain to spinal cord motor neurons except the pyramidal tracts
- numerous relays of motor neurons between motor areas of ortex, thalamus, cerebellum, and brainstem
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extrapyramidal system tract
- message begins in motor strip/precentral gyrus
- continue to corona radiata
- now to deep brain structures
- this includes cerebellum, basal ganglia, thalamus, sustantia nigra
- multiple synapses occuring
- meet up with the pyramidal system in the brainstem or spinal cord at the lower motor neuron at the point of synapse
- travel with pyramidal system to muscle
- ensues smooth, coordinated movements
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Motor tract of Biceps Brachii
- message initiation begins in motor strip/precentral gyrus of brain
- pathways continues through corona radiata
- through the internal capsule
- through the medulla oblongata
- decussation occurs
- 3/4 crossed fibers go to lateral horn of spinal column
- 1/4 not crossed fibers go to anterior horn of spinal column
- THIS IS ALL BY WAY OF UPPER MOTOR NEURON
- synapse occurs here
- message travels by way of axon
- to myoneural junction
- to bicceps branchii muscles
- contraction for movement of the arms occurs
- THIS IS A LOWER MOTOR NEURON
- THIS IS ALL A CORTICOSPINAL TRACT
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Extrapyramidal system of biceps brachii tract
- message begins in motor cortex/precentral gyrus
- continue to corona radiata
- now to deep brain structures
- this includes cerebellum, basal ganglia, thalamus
- multiple synapses occuring
- meet up with pyramidal system in the spinal column at the lower motor neuron at the point of synapse
- travel with pyramidal system to muscle
- ensues smooth, coordinated movements
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in the extrapyramidal system the only step that changes in step #
- 6.
- spinal column - corticospinal nerves
- brainstem - corticobulbar nerves
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Posterior Cricoarytenoid Muscle tract
- message initiation begins in motor cortex/precentral gyrus of the brain
- pathway continues through the corona radiata
- through the internal capsule
- through the medulla oblongata
- THIS IS ALL BY WAY OF UPPER MOTOR NEURON
- synapse occurs in medulla oblongata
- message travels by cell body by way of axon of cranial nerve X vagus
- to myoneural junction
- to posterior cricoarytenoid muscle
- contraction for abduction of vocal folds occurs
- THIS IS A LOWER MOTOR NEURON
- THIS IS A CORTICOBULBAR TRACT
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cranial nerves I and II...
- do not have a motor component
- we will not be asked to trace
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extrapyramidal system of posterior cricoarytenoid muscles
- begins in motor strip/precentral gyrus
- continue to corona radiata
- travels to deep brain structures
- includes cerebellum, thalamus, basal ganglia
- multiple synapses occuring
- meet up with pyramidal system in the medulla at the point of synapse with the LMN
- ensues smooth, coordinated movements
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