the dorsal column-medial lemniscal system
DESCRIPTION
The Dorsal Column-Medial Lemniscal System. "I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use." - Galileo Galilei. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
The Dorsal Column-Medial Lemniscal System
"I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to
forgo their use." - Galileo Galilei
Introduction
• The dorsal column-medial lemniscus system conveys somatic discriminative sensory information from touch, vibration, and joint position receptors
• Throughout the system, the fibers are arranged somatitopically in relation to their entry into the CNS
• The cell bodies reside in the dorsal root and trigeminal ganglia
Synapsing in the cord
The fibers from the lower
limbs synapse on the
Gracile Nucleus.
Those from the upper limbs synpase on theCuneate Nucleus.
Gracile
Cuneate
From below the belt (and above it)
The fibers from the leg, trunk, andarm ascendipsilaterally as the dorsal
columns
L5
C8
C1
The great cross over
Axons leaving the
dorsal columnnuclei cross asarcuate fibers
andAscend as thecontralateral medial
lemniscus.
Medulla
What about the face?
At the level of thebrainstem,
primarysensory axons
fromthe face synapsein the principle trigeminal nucleusand cross to join the contralateral medial lemniscus.
Midbrain
Pons
Up, up , and away!
The medial lemniscus ascends to the
ventralposterior thalamic nucleus
• Lateral Division (VPL) - Leg, Trunk, and Arm
• Medial Division (VPM) - Face
Top Floor - 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 dorsal column-lemniscal
system eventually terminates on the postcentral gyrus
of the brain.
The Homunculus!The arrangement of fibers correlates totheir entry into the spinal cord.
Legs, feet,ankles
Shoulder,arms, abdomen
Hand(large thumb)
Face
Tongue
And now for the movie….
QuickTime™ and aSorenson Video decompressorare needed to see this picture.