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Robotic Spine Universe

Pathways

Spinothalamic tract

Pain and temperature

Pain and temperature fibres synapse as soon as they enter the cord; the second neuron crosses within the cord and climbs the opposite side to the thalamus. A cord lesion on one side therefore takes away pain and temperature on the other.

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 cordBody123456

Step by step

  1. Receptor in the skin · served side
  2. Dorsal horn: synapse, then the axon crosses · served side · synapse · crosses the midline
  3. Spinothalamic tract (opposite side) · other side
  4. Brainstem · other side
  5. Thalamus · other side · synapse
  6. Primary sensory cortex · other side

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

Where it runs in the cord (L5)

left fasciculus gracilisright fasciculus gracilisleft fasciculus cuneatusright fasciculus cuneatusleft lateral corticospinal tractright lateral corticospinal tractleft spinal lemniscusright spinal lemniscusleft ventrolateral reticulospinal tractright ventrolateral reticulospinal 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 (spared)
  • right lateral corticospinal tract (spared)
  • left spinal lemniscus (focus)
  • right spinal lemniscus (focus)
  • left ventrolateral reticulospinal tract (spared)
  • right ventrolateral reticulospinal 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

In the PAM50 white-matter atlas used for the cross-sections, this region is labelled the spinal lemniscus (spinothalamic and spinoreticular tracts).

What the sources say

“Axons from these second neurons decussate within the spinal cord, then they ascend to the brain and enter the thalamus where each synapses with the third neuron in its respective pathway.” Betts et al. 2022, §14.2
“The dorsal column system is primarily responsible for touch sensations and proprioception, whereas the spinothalamic tract pathway is primarily responsible for pain and temperature sensations.” Betts et al. 2022, §14.2

Sources: Betts et al. 2022, §14.2