Cerebellum: Anatomy and Function Overview

Introduction

• Lecture Focus: Cerebellum
• Views Covered: Anatomical lateral, posterior, internal circuitry (deep cerebellar nuclei), and associated pathways

General Anatomy

• Location: Posterior cranial fossa of the skull
• Separation from Cerebrum: Tentorium cerebelli (dural septa)
• Surface Anatomy:
  • Folia: Folds increasing surface area
  • Outer Grey Matter: Unmyelinated cell bodies and dendrites
  • Arbor Vitae (Tree of Life): Central white matter, containing myelinated axons

Structural Anatomy

• Fissures:
  • Primary Fissure
  • Posterior Lateral Fissure
• Lobes:
  • Anterior Lobe
  • Posterior Lobe (newer part of the cerebellum)
  • Flocculonodular Lobe (primitive)
• Function:
  • Balance and equilibrium (connected with inner ear)
  • Muscle tone
  • Coordination of movement
  • Motor learning (via connections to cortical areas)

Functional Zones

• Anterior Lobe: Spinocerebellum
• Posterior Lobe: Cerebrocerebellum
• Flocculonodular Lobe: Vestibulocerebellum (archicerebellum)

Detailed Functional Anatomy

• Functional Lobes:
  • Anterior Lobe (Spinocerebellum): Vermal and paravermal (intermediate) zones
    • Sensory Homunculus (Ascending Proprioceptive Information):
      • Axial skeleton and extremities
  • Posterior Lobe (Cerebrocerebellum): Lateral Hemispheres
  • Flocculonodular Lobe (Vestibulocerebellum); related to vestibular system (balance and equilibrium)

Deep Cerebellar Nuclei

• Mnemonics: Don’t Eat Greasy Food
  • Dentate Nucleus: Lateral Hemisphere, connects to red nucleus and thalamus
  • Interposed Nucleus: Globose and Emboliform nuclei (vermal and paravermal zones)
  • Fastigial Nucleus: Flocculonodular lobe; also vermis

Internal Circuitry

• Cerebellar Cortex Layers:
  • Molecular Layer
    • Stellate cells
    • Basket cells
    • Parallel fibers of granule cells
  • Purkinje Layer
    • Purkinje cells (output inhibitory—GABA)
  • Granular Layer
    • Granule cells
    • Golgi cells
• Fiber Pathways:
  • Climbing Fibers (from inferior olives, stimulate deeply)
  • Mossy Fibers (from various sensory pathways, granule to Golgi cells)
• Neural Sharpening: Ensures precise motor responses

Pathways Overview

Superior Cerebellar Peduncles (SCP)

• Efferent Pathways: Information out
  • Dentate Nucleus: to contralateral red nucleus or thalamus
    • Dentothalamic Pathway
    • Dentorubrothalamic Pathway
    • Rubrospinal Pathway
  • Interposed Nucleus (Globose & Emboliform): Particularly to red nucleus
• Afferent Pathways: Information in
  • Ventral Spinocerebellar Tract and others

Middle Cerebellar Peduncles (MCP)

• Primary Afferent Pathways from Cortex: Corticopontocerebellar Fibers
  • Carry motor plan for coordination

Inferior Cerebellar Peduncles (ICP)

• Afferent Pathways:
  • Dorsal Spinocerebellar Tract (proprioceptive below L2/L3)
  • Cuneocerebellar Tract (proprioceptive above C8)
  • Vestibulocerebellar Pathway (inner ears)
  • Olivocerebellar Pathway (inferior olives)
  • Reticulocerebellar Pathway
• Efferent Pathways:
  • Cerebellar Reticular
  • Cerebellar Vestibular

Summary

• Main Functions: Balance, muscle tone, coordination, motor learning
• Key Connections: Links to vestibular system, proprioceptors, and cerebral cortex
• Nuclei: Dentate, Interposed (Globose & Emboliform), Fastigial
• Internal Circuitry: Climbing and mossy fiber pathways, neural sharpening via inhibitory and excitatory neurotransmitters

Conclusion

• Pathways: Numerous afferent and efferent pathways connecting to spinal cord, cortex, and brainstem nuclei
• Practice and Study: Essential for mastering cerebellar functions and connections