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Spinothalamic system

The spinothalamic tract is the principal pathway transmitting noxious, thermal, and visceralinformation to the thalamus and cortex

Contents

Origin

  • Lamniae I
  • Laminae V
  • Lamina VII

Laminae I

  • Processes information from nociceptors, thermal receptors, visceral afferents, or itch receptors

Laminae V

  • Processes information from tactile, visceral, thermal and noxious stimuli

Laminae VII

  • Processes information from large areas of the body, including viscera
  • Since this laminae covers such a wide area it has limited ability to pinpoint and localize the origin of the sensory stimuli
  • Also this laminae projects this information to nuclei in the thalamus which are more involved in affective responses to stimuli than in identification and localization of stimuli

Decussation of spinothalamic fibers in the spinal cord

  • Noxious and thermal information from each dermatome is transmitted contralaterally in the anterolateral column
    • As a result, when an injury occurs in the spinal cord, thermal or painful sensations are disturbed or lost on the opposite side of the body compared to the location of the lesion
  • Touch and proprioception are transmitted ipsilaterally in the dorsal column
    • As a result, when an injury occurs in the spinal cord, touch and proprioceptiveinformation is disturbed or lost on the same side of the body compared to the location of the lesion
  • The somatosensory submodalities of touch, proprioception, temperature, and pain are reunited on the contralateral side of the neuraxis higher in the pons as the mediallemniscus and spinothalamic tract approach the thalamus

Signaling

  • For the dorsal column:
    • Tactile and limb proprioception signals are transmitted to the spinal cord where it either:
      1. Branches to the spinal grey matter
      2. Transmits to the brainstem and further to the thalamus
    • In the thalamus, the signal terminates in the lateral and medial ventral posteriornuclei. These nuclei convery tactile and proprioceptive information to the primary somatic sensory cortex
  • For the anterolateral system:
    • Pain, itch, temperature, and visceral information is conveyed to the spinal cord that terminate in the dorsal horn
    • This information is convyed across the midline (decussates) within the spinal cord and transmitted to the brainstem and the thalamus

Important to note

  • The spinothalamic tract is joined by axons from the trigeminal nucleus caudalis