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11 Cards in this Set
- Front
- Back
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what is the primary afferent input to the trigeminal discriminative touch system
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mechanoreceptors from any of the three branches of the trigeminal nerve
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where do the primary afferents of the trigeminal discriminative touch system synapse
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the chief senosry nucleus of V in the pons on the ipsilateral side
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The primary afferents of the trigeminal discrim. system synpase in the cheif sensory nucelus of V in the pons on the ipsilateral side. Where do the second order neurons go?
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2nd order neuns send fibers that cross to the other side of the pons and form the trigeminal lemniscus which joints the medial lemniscus. They then ascend to the VPM nucelus of the thalamus and terminate on third order neurons.
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Describe the somatotopy of the head and face in the VPM of the thalamus
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tongue is medial ,face is lateral
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Describe the course of the minor pathway for crude touch of the trigeminal discrim. system
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the mechanoreceptors enter the pons and descend in the spinal tract of V to the spinal nucelus of 5 in the caudal medulla and synapse. 2nd order neurons then cross the midline ans ascend in the trigeminothalamic tract to the VPM
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Describe the course of the minor pathway for oral cavity sensation in the trigeminal discrim. system
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Mechanoreceptors from the oral cavity enter the pons and synapse in the cheif nucleus. 2nd order neurons don't cross (like the major touch pathway would) but rather ascend on the ipsilateral side via the dorsal trigeminal tract to the VPM.
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Fibers from the trigeminal discrim. pathways synapse in the VPM of the thalamus. Where do the 3rd order thalamic neurons project
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Through the posterior limb of the internal capsule and corna radiata and terminate in the lateral aspect of SI cortex (near lateral fissure)
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Fibers carrying fine touch from the body and face enter tracts at different levels of the brain stem but rostrally they run together in the medial/trigeminal lemniscus. Where do fibers from the face and body enter?
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face=pons , body=medulla
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describe the path of the first order trigeminal pain fibers
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enter in nerve V at the pons and descend ipsilaterally in the spinal trigeminal tract terminating in the spinal nuclues of V in the caudal medulla
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Describe the path of the second order neurons of the trigeminal pain system
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Axon from the spinal trigeminal nucleus of V in the caudal meduall cross to the other side of the medulla and ascend as the trigeminothalamic tract along side anterolateral (spinothalamic) tracts to the VPM of the thalamus
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Describe the path of the 3rd order neurons of the trigeminal pain system
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3rd order neurons from the VPM project through the posterior limb of the internal capsule and corona radiata up to the lateral SI cortex, some project to the reticular formation
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