Anatomy of the Central Nervous System: The Cerebellum

Introduction

• Central nervous system consists of:
  • Encephalon
  • Spinal cord
• Encephalon parts:
  • Brainstem: Medulla, Pons, Midbrain (mesencephalon)
  • Cerebellum
  • Diencephalon
  • Telencephalon

Focus on Cerebellum

• Covered Topics:
  • Topography
  • Functions
  • External surface
  • Internal surface (cross-section)
    • Gray matter nuclei
    • White matter tracts

Topography

• Cerebellum is located behind the Pons and Midbrain

Functions of the Cerebellum

• Regulates muscle contractions for smooth movements
• Coordinates balance and posture
• Regulates muscle tone for joint stability
• Engages in smooth voluntary movements (e.g., writing)
• Most fibers from the cerebral cortex

External Structure

• View from posterior:

  • Two hemispheres
  • Vermis in the middle
  • Surface has grooves (sulci) and bumps (Folia)
  • Fissures:
    • Primary Fissure: separates Anterior and Posterior Lobes
    • Posterolateral Fissure: separates Posterior Lobe from Flocculonodular Lobe

• View from anterior:

  • Cerebellar Peduncles
    • Connect Cerebellum to brainstem
    • Inferior: to Medulla
    • Middle: to Pons
    • Superior: to Midbrain

Internal Structure

• Gray Matter:

  • Surface forms cerebellar cortex
  • Contains:
    • Dentate nucleus: unconscious muscle coordination
    • Fastigial nucleus: connects to vestibular system (balance and posture)
    • Globose and emboliform nuclei: sensory input for proprioception

• White Matter:

  • Contains tracts resembling branches of a tree (arborvitae)
  • Tracts go in and out via peduncles

Tracts and Pathways

• Afferent Fibers (Sensory):

  • Vestibular system fibers through inferior peduncle
  • Spinocerebellar tracts:
    • Posterior: through inferior peduncle
    • Anterior: through superior peduncle
  • External arcuate fibers from brainstem
  • Olivary nucleus fibers through inferior peduncle

• Efferent Fibers (Motor):

  • Cerebellorubral/Dentatorubral tracts to Midbrain
  • Corticopontine tract:
    • From cerebral cortex lobes to Pons
    • Contributes to smooth, precise voluntary movements

Conclusion

• Importance of Cerebellum in coordination, posture, and balance
• Reminder to utilize resources for further study