Cord Syndromes

Anatomy of the Spinal Cord Tracts

• Motor:
  • Anterior horn (cell bodies of motor neurons)
  • Lateral corticospinal / pyramidal tract
    • Begins in primary motor cortex
    • Descends on ipsilateral side through thalamus, reaching the medulla
    • Crosses at medullary pyramid
    • Then descends in contralateral cord
• Sensory:
  • Lateral spinothalamic / anterolateral tract (pain and temperature)
    • Sensory fibres enter ipsilateral cord via dorsal root
    • Immediate decussation across the anterior commissure, just anterior to the central canal
    • Thereafter ascends to thalamus in the contralateral cord
  • Dorsal column (vibration, pressure, proprioception)
    • Ipsilateral on entering cord, ascends on ipsilateral side to ipsilateral cuneate and gracilis nuclei
      • Fasciculus cuneatus – upper limb
      • Fasciculus gracilis – lower limb
    • Second order neurons from these nuclei then decussate and run towards the thalamus (ventral posteromedial nucleus)