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General features of sensory pathways
- relevant stimuli: light touch, vibration, proprioception, pain, temperature
- sensory stimuli from body enter the pineal cord
- sensory stimuli from the head enter the brainstem via cranial nerves
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Sensory receptors:
- modified nerve endings
- bare nerve endings
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Common aspects of pathways
- pathways carry info for perception and reflexes
- 3-neuron pathways for perception - begin in periphery, end in cortex
- locations of axons (tracts) and cell bodies (nuclei)
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primary cell body located in
dorsal root ganglion
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primary axon located in
dorsal root
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secondary cell body in
- spinal cord or brain stem
- secondary axon crosses CNS
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tertiary cell body in
thalamus
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tertiary axon goes through
internal capsule
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spinal cord laminae
precise "geographic" regions of the gray matter where defined by Rexed and numbered from 1 to IX; these correspond to named regions such as Nucleus Proprius, but numbers are more precise
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Lamina II
substantia gelatinosa
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laminae III-VI
nucleus proprius
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Lamina VII
Clarke's nucleus
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Laminae VIII-IX
Motor nuclei
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