The Human Brain : From Neurone to Nervous System

THE MAIN ASCENDING SPINAL PATHWAYS


  1. Ascending Spinal Pathways carry information from the Spinal Cord to higher levels of the Central Nervous System.

  2. Large myelinated neurones with cell bodies in the dorsal root ganglia give rise to axon collaterals that project through the dorsal column-medial lemniscal pathway, which carries information about touch and vibration to the dorsal column nuclei (cuneate and gracile nuclei) in the caudal medulla.

  3. The dorsal column nuclei process the information by introducing a degree of spatial contrast (edge detection) and this information is passed to the contralateral ventro-basal thalamus, which in turn processes and relays somatosensory signals to the primary receiving areas of the cerebral cortex in the post-central gyrus.

  4. The Spinothalamic pathway processes nociceptive signals carried by unmyelinated sensory axons in the ipsilateral dorsal horn, and the output neurones have long axons that ascend to the ventral postero-lateral thalamic nuclei.

  5. The Anterolateral System consists of the spinothalamic tract and other pathways carrying nociceptive signals that synapse en route to the posterior thalamus.

  6. The spino-cerebellar tracts carry information about the position of limbs to the cerebellum. This is an ipsilateral pathwaythat is used in the coordination of movements and balance.

  7. Key Words: Dorsal Columns, Dorsal column nuclei, medial lemniscus, thalamus: dorsal column-medial lemniscal system concerned with touch and vibration.
    Spino-thalamic and Spino-reticular pathways concerned with pain and temperature sensation.
    Spino-cerebellar pathways concerned with cerebellar inputs from proprioceptive neurones.








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