Transcript The Anterolateral System

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