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Ascending tracts 2

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1st order neuron
      The axons enter the spinal cord from the posterior
      root ganglion & pass directly to the posterior
      white column of the same side
      The ascending fibers travel upward in the white
      column as the fasciculus gracilis & cuneatus
      Fasciculus gracilis is present throughout the spinal
      cord (Contain ascending fibers from the sacral,
      lumbar & lower 6 thoracic spinal nerves)
      Fasciculus cuneatus is situated lateral to the FG in
      the upper thoracic & cervical segments (Contain
      ascending fibers from upper 6 thoracic & cervical
      spinal nerves)
      FG & FC ascends ipsilaterally & synapses with the
      2nd order neurons at medulla oblongata


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2nd order neuron

  1)The axons are called internal arcuate fibers
  2)They decussate with the corresponding fibers from the opposite
  side in the sensory decussation
  3)The fibers then ascend as a compact bundle called the medial
  lemniscus through medulla, pons & midbrain
  4)The fibers synapse with the 3rd order neuron in the ventral
  posterolateral nucleus of the thalamus
  5)Some fibers from the FC enter the cerebellum through the
  inferior cerebellar peduncle of the same side (Cuneocerebellar
  tract)                                     www.medicallecturenotes.com
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The   Main sensory pathways to consciousness




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Unconscious muscle joint sense pathways to
             the cerebellum




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Unconscious muscle joint sense pathways to
             the cerebellum




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Other ascending pathways




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posted:3/2/2012
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