Lecture Notes: Spinal Cord and Ascending Pathways

Overview

• Focus on sensory signals (afferent) from external/internal environment to brain and brainstem.
• Spinal cord anatomy: grey matter and white matter.

Spinal Cord Anatomy

• Grey Matter: Located in the center, where neurons synapse and integrate information.
• White Matter: Surrounds grey matter; comprises pathways for signals going to (ascending) or from (descending) the brain.
  • Ascending pathways carry sensory (afferent) information.
  • Descending pathways carry motor (efferent) information.

Sensory Information Pathways

• Sensory information enters spinal cord dorsally (back side).
• Motor information exits spinal cord ventrally (front side).

Dorsal Column Medial Lemniscus Pathway

• Carries fine touch and conscious proprioception.
• Decision pathways:
  • Below Thoracic Level 6: Uses the Fasciculus Gracilis.
  • Above Thoracic Level 6: Uses the Fasciculus Cuneatus.

Spinocerebellar Tracts

• Relates to proprioception and balance.
• Dorsal Spinocerebellar Tract:
  • Transmits information from the same side to the cerebellum.
  • Associated with information during movement.
• Ventral Spinocerebellar Tract:
  • Transmits information by crossing sides twice before reaching the cerebellum.
  • Conveys information about movement.

Anterolateral System

• Two major types: Lateral Spinothalamic and Ventral Spinothalamic.

Lateral Spinothalamic Tract

• Handles pain and temperature sensations.
• Pathway based on body region:
  • Medial: cervical (neck) region.
  • Lateral: thoracic, lumbar, and sacral regions.
• Key characteristic: Pain signals cross immediately to the opposite side.

Ventral Spinothalamic Tract

• Handles crude touch and pressure.
• Crude touch signals cross at the brainstem, while pain crosses immediately within the spine.

Conclusion

• Next focus: Motor output pathways.