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Robotic Spine Universe

Pathways

Lateral corticospinal tract

Voluntary movement of the limbs

The main route for voluntary movement. Upper motor neurons in the motor cortex send axons down through the internal capsule, the cerebral peduncle and the pons; in the medulla most cross to the other side and run down the lateral cord to the lower motor neurons that drive the muscles.

Drawn for the left side of the body. Schematic route through the model’s landmarks; the pulse speed is illustrative.

Route

served sideother sideCortexDeep brainMidbrainPonsMedullaSpinal cordBody12345678

Step by step

  1. Primary motor cortex (upper motor neuron) · other side
  2. Internal capsule · other side
  3. Cerebral peduncle · other side
  4. Pons · other side
  5. Pyramid, then the pyramidal decussation · other side · crosses the midline
  6. Lateral corticospinal tract · served side
  7. Ventral horn (lower motor neuron) · served side · synapse
  8. Muscle · served side

Schematic Filled circles: synapses. X: the pathway crosses the midline. Numbers match the list.

Where it runs in the cord (L4)

left fasciculus gracilisright fasciculus gracilisleft fasciculus cuneatusright fasciculus cuneatusleft lateral corticospinal tractright lateral corticospinal tractleft rubrospinal tractright rubrospinal tractleft spinal lemniscusright spinal lemniscusleft ventrolateral reticulospinal tractright ventrolateral reticulospinal tractleft lateral vestibulospinal tractright lateral vestibulospinal tractleft ventral corticospinal tractright ventral corticospinal tractleft tectospinal tractright tectospinal tractleft medial reticulospinal tractright medial reticulospinal tractleft medial longitudinal fasciculusright medial longitudinal fasciculusleft ventral hornright ventral hornleft intermediate zoneright intermediate zoneleft dorsal hornright dorsal hornAnteriorPosteriorLR
  • Ascending (sensory)
  • Corticospinal (motor)
  • Other descending
  • Grey matter
Regions in this section (text list)
  • left fasciculus gracilis (spared)
  • right fasciculus gracilis (spared)
  • left fasciculus cuneatus (spared)
  • right fasciculus cuneatus (spared)
  • left lateral corticospinal tract (focus)
  • right lateral corticospinal tract (focus)
  • left rubrospinal tract (spared)
  • right rubrospinal tract (spared)
  • left spinal lemniscus (spared)
  • right spinal lemniscus (spared)
  • left ventrolateral reticulospinal tract (spared)
  • right ventrolateral reticulospinal tract (spared)
  • left lateral vestibulospinal tract (spared)
  • right lateral vestibulospinal tract (spared)
  • left ventral corticospinal tract (spared)
  • right ventral corticospinal tract (spared)
  • left tectospinal tract (spared)
  • right tectospinal tract (spared)
  • left medial reticulospinal tract (spared)
  • right medial reticulospinal tract (spared)
  • left medial longitudinal fasciculus (spared)
  • right medial longitudinal fasciculus (spared)
  • left ventral horn (spared)
  • right ventral horn (spared)
  • left intermediate zone (spared)
  • right intermediate zone (spared)
  • left dorsal horn (spared)
  • right dorsal horn (spared)

Highlighted: the region of the PAM50 white-matter atlas for this pathway, on both sides of the cord. A lesion here takes away what it carries below the level, on the side its fibres serve at that point.

Cut it on the left in the lesion explorer

What the sources say

“It then passes between the caudate nucleus and putamen of the basal nuclei as a bundle called the internal capsule.” Betts et al. 2022, §14.3
“The tract then passes through the midbrain as the cerebral peduncles, after which it burrows through the pons.” Betts et al. 2022, §14.3
“The defining landmark of the medullary-spinal border is the pyramidal decussation, which is where most of the fibers in the corticospinal tract cross over to the opposite side of the brain.” Betts et al. 2022, §14.3
“The lateral corticospinal tract is composed of the fibers that cross the midline at the pyramidal decussation (see Figure 14.28).” Betts et al. 2022, §14.3

Sources: Betts et al. 2022, §14.3