The Anterolateral System

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The Anterolateral System

• Pain and Temperature Transmision

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• The Anterolateral System is an ascending pathway
  conveying pain and temperature sensation.
• Cell bodies of the primary sensory neurons
  reside in the dorsal root ganglia and the
  trigeminal complex.
• This pathway receives input from thermoreceptors,
  nociceptors, and mechanoreceptors.

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Getting into the Spinal Cord

• Primary axons synapse in Rexed layers I-IV of the
  dorsal horn
• Secondary axons cross in the anterior white
  column to form the anterolateral tract.

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Sensation from the face

• Pain and temperature sensation from the face are
  conveyed from fibers in the spinal trigeminal
  complex.
• These fibers cross in the brain stem and join the
  anterolateral tract.

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Connections in the brain stem

• ALT axons distribute to the reticular formation,
  central gray substance, and finally the
  intralaminar and posterior thalamus
• The neospinothalamic tract distributes
  somatotopically in the ventral posterior
  thalamus
• VPL - Leg, Trunk, Arms
• VPM - Face

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To the Cortex
From the VPL and the VPM of the thalamus, the
fibers extend to the primary sensory cortex
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Primary Sensory Cortex
Sensory information from the ALS eventually
terminates on the postcentral gyrus of the brain.
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The Homunculus!
Shoulder, arms, abdomen
Hand (large thumb)
Face
The arrangement of fibers correlates to their
entry into the spinal cord.
Legs, feet, ankles
Tongue
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And Now for the Movie..