Laboratory 12 : Tract Systems I
  Somatosensory System : Trigeminothalamic Tract

Trigeminothalamic Tract

It is important to note that:

  • This tract contains somatosensory info from head.
  • Tract decussates either at level of rostral medulla (synapses on main sensory nucleus of cranial nerve V) or at caudal medulla (synapses on STN)
  • Contains info about all somatosensory submodalities.


Slide 91 : Telencephalon

  • Synapses on face/head area of 1º somatosensory cortex.

Slide 60 : Diencephalon

  • These fibers synapse in the VPM in the thalamus.
  • Then, VPM axons project up to 1º somatosensory cortex.

Slide 37 : Rostral Medulla

  • Signals coming from face and head come in via cranial nerve V (Trigeminal).
  • Another collateral synapses on main sensory nucleus of cranial nerve V in the rostral medulla, main sensory neuron axon decussates and enters the medial leminiscus and goes up to thalamus.

Slide 16 : Caudal Medulla

  • A collateral sensory neuron goes to medulla, where it synapses on the spinal trigeminal nucleus (STN).
  • STN neuron axon decussates and enters medial lemniscus to ascend to thalamus.

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