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17 Cards in this Set
- Front
- Back
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three-neuron organization of the somatosensory system
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1st order: cell bodies in dorsal root ganglion
2nd order: in the CNS either in spinal cord or brainstem 3rd order: contralateral thalamus |
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ALS
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pain, temp, crude touch from body
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DCML
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fine touch, conscious proprioception from body
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Trigeminal
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all somatosensation except head and neck
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Spinocerebellar
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unconscious proprioception
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ALS Decussation
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Spinal cord
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ALS pathway
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1st order: dorsal root
2nd order: dorsal column neuron crosses in the anterior white matter Lateral spinothalamic tract: pain & temperature Anterior spinothalamic tract: crude touch (immediately crosses) 3rd order: ventral post. lat. nucleus in thalamus Goes up to sensory cortex in parietal lobe |
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DCML pathway
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1st order: dorsal root
Arm & upper body paired (fasciculus cuneatus) & leg & lower body paired (fasciculus gracilis) 2nd order: in medulla (arm&upb: n.cuneatus & leg&lwb: nucleus gracilis) cross at medulla (lemniscal decussation) 3rd order: thalamus up to the sensory cortex in the parietal lobe |
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Trigeminal system pathway
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somatosensory information for the head
some fine fiber stays ipsilateral & it uses the VPM |
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Thalamus Ventral posterior-lateral Nucleus (VPL):
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where ALS and DCML 2nd order neurons synapse with 3rd order
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Thalamus Ventral posterior-median nucleus (VPM):
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where Trigeminal pathway 2nd order neurons synapse with 3rd order
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Trigeminal pathway
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1st order: cell bodies in semilunar ganglion projection
2nd order: synapse in the trigeminal nuclear complex Projections from the spinal tract nucleus cross the midline and terminate in the VPM Projections from the chief sensory nucleus project to the ipsilateral and contralateral VPM 3rd order: sensory fibers travel through internal capsule to the postcentral gyrus, the primary sensory area for the face |
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Spinocerebellar pathway
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sensations that do not reach consciousness are mediated by the rostral spinocerebellar tracts and others
- sensation of limb position, joint position, range and direction of limbs |
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Spinocerebellar Pathway
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transmits unconscious proprioception from muscle spindles and limb joints to the cerebellum to help monitor and modify movements, and a lot/most of the information is processed ipsilaterally
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Cortical or subcortical lesion
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A lesion at this level is manifested by parasthesia (tingling) and numbness in the corresponding regions of the trunk and limbs on the opposite side of the body
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Subthalamic Lesion
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All sensation is abolished in the contralateral half of the body. A partial lesion that spares the pain and temp pathways is characterized by hypesthesia (decreased tactile sensation) on the contralateral face and body.
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Gustation
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1st order: either of CN VII, IX, or X in the ganglion outside the brainstem (nucleus tractus solitarius)
some of it stays ipsilateral and some stays contralateral some gets processed outside of thalamus > anterior insula |
