Laboratory 12 : Tract Systems I
  Somatosensory System : Dorsal Column Medial Lemniscal Tract

Dorsal Column Medial Lemniscal Tract


It is important to note that:

  • This tract carries somatosensory info from entire spinal cord: limbs and trunk .
  • Decussation occurs in caudal medulla after synapsing on nucleus gracilis and nucleus cuneatus.
  • This tract transmits info about touch, pressure, vibrations, joint position, muscles, and tendons.
  • It does NOT transmit info about pain or temperature (like Neospinalthalmic Tract does)
  • Since it’s a specific tract, it is somatotopic and submodality specific.

 

Slide 90 : Telencephalon

  • Synapses in 1º somatosensory cortex in cerebrum.

Slide 67 : Diencephalon

  • Synapses with VPL (lateral projection nuclei) in thalamus.
  • Transmits through internal capsule to cerebrum.
  • Procedes towards 1º somatosensory cortex.

Slide 45 : Pons/Midbrain

  • Passes through medial leminiscus.

Slide 26 : Medulla

  • Continues through medial leminiscus.

Slide 18 : Caudal Medulla

  • Tract from upper half of body enters fasciculus cuneatus, then nucleus cuneatus.
  • Lower half enters fasciculus gracilis, then nucleus gracilis.
  • Sensory collaterals synapse on neurons of either nucleus cuneatus or nucleus gracilis.
  • Cuneate or gracile axons (internal arcuate fibers) decussate, entering medial leminiscus.

Slide 8: C1

  • Sensory neurons enter from upper half of the body into dorsal root, and collaterals pass through dorsal funiculus.

Slide 2 : L6

  • Sensory neurons enter from lower half of the body into dorsal root and collaterals pass through dorsal funiculus.

Copyright © 2006 - University of Pennsylvania School of Veterinary Medicine, All rights reserved.
Faculty: Dr. Richard Miselis, Dr. Peter Hand
Students: Natalie Fickel V'12, Ryan Donahue V'09, Cara Catanese V’08, Rebecca Wolf V'06, Keith Javic V'03, Ken Bixel V'99, Russel Howe-Smith V'97