Laboratory 12 : Tract Systems I
  Somatomotor System : Corticospinal Tract

Corticospinal Tract

It is important to note that:

  • Decussation occurs for the majority of the fibers in this tract.
  • This tract projects to all spinal cord segments.
  • This tract is part of the dorsolateral group, so it innervates distal musculature (i.e. distal forelimb and hindlimb).


Slide 97 : Telencephalon

  • Begins in 1º motor cortex.
  • 1º motor cortex signals can be modified by premotor and supplementary (association) motor areas.

Slide 84 :

  • Axons pass from cerebral cortex through internal capsule.

Slide 49 : Midbrain

  • Axons are in cerebral peduncle.

Slide 40 :

  • Axons continue through ventral pons (corticospinal tract (CST))

Slide 35 :

  • Axons enter pyramids at the rostral medulla .

Slide 13 : Caudal Medulla Oblongata

  • Axons decussate at the caudal extent of the medulla.

Slide 6 : C7

  • Axons descend in the dorsolateral funiculus.
  • Then, synapses in laminae V, VI, VII, and IX.
  • Synapse on interneurons, sending commands to alpha- and gamma- motoneurons in Lamina IX.

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