FNS 25 Cerebellum

• 1. Ipsilateral movement planning/coordination
• 2. Maintaining posture and balance
• 3. Controlling eye movements

Granule, Purkinje and molecular layers

White matter - axons to and from the cerebellar cortex

Four pairs of deep cerebellar nuclea in the medullary substance

• Fastigial
• Globose
• Emboliform
• Dentate

ICP: medulla to cerebellum

MCP: pons to cerebellum

SCP: midbrain to cerebellum

Vestibulocerebellum (flocculonodular lobe)

Spinocerebellum (vermis and medial hemispheres)

Pontocerebellum (lateral hemispheres)

Somatotopically:

• lower limbs - anteriorily
• upper limbs - posteriorily
• proximal - medially
• distal - laterally

• 1. Primary Afferent Fibers
• uncrossed from bipolar neurons of vestibular ganglion

• 2. Secondary Afferent
• uncrossed from vestibular nuclei

• 1. PSCT - Posterior Spinocerebellar Tract
• uncrossed from Dorsal Nuc of Clarke
• lower limb proprioception

• 2. CCT - Cuneocerebellar Tract
• uncrossed from Accessory Cuneate Nuc
• upper limb proprioception

• 3. ASCT - Anterior Spinocerebellar Tract
• double-crossed from spinal intermediate zone
• Golgi tendon info

• 4. Spinoreticulo-Cerebellar Pathways
• uncrossed from lateral reticular nucleus

• 5. Trigeminocerebellar Fibers
• uncrossed from CN V sensory nuclei

• crossed from pontine nuclei via MCP
• serves as communication between cerebral cortex and contralateral pontocerebellum

Crossed from Inferior Olivary Complex via ICP

Terminate as climbing fibers on Purkinje cells in each cerebellar subdivision

Mossy Fibers - synapse on granule cells

Climbing Fibers - synape on Purkinje cells

Found in granule cell layers

Excitatory synapses with dendrites of granule cells and deep cerebellar neurons

Indirectly stimulate Purkinje Cells

Used for moment-to-moment coordination

Bifurcate and ascent into molecular layers as Parallel Fibers

Excitatory synapses on Purkinje dendrites and all inhibitory interneurons

Interneurons which inhibit granule cell dendrites within the cerebellar glomeruli

• Granule cell dendrites
• Mossy fiber axon terminal
• Golgi cell axon terminal
• Glial capsule

• Inhibit deep cerebellar neurons using GABA
• Only output of cerebellar cortex

• Climbing Fibers
• Parallel Fibers
• Basket Cells
• Outer Stellate Cells

• From IOC
• Excite Purkinje cells and deep cerebella nuclei
• Fuctions include movement synchronization and motor learning

• Excited by parallel fibers
• Inhibit purkinje cell somata

• Excited by parallel fibers
• Inhibit Purkinje cell dendrites

Purkinje cells in Flocculonodular Lobe synapse directly on vestibular nuclei

Ipsilateral Righting Reflex and Eye Coordination

• Purkinje cells in the vermis to Fastigial Nuc
• Ipsilateral axial muscle control for posture/balance

• Pukinje cells in paravermis to Globose and Emboliform Nuc
• Terminate contralaterally in Red Nucleus and thalamus
• Fine control of distal muslces

• Purkinje cells in pontocerebellum to Dentate Nuc
• Cross to Red Nucleus and thalamus
• Planning of Complex Movements

• Vestibulocerebellum affected
• symptoms: ataxic gait, head tremor, nystagmus
• Recumbent improvement

• Often alcohoic degeneration
• Symptoms: truncal ataxia

• Ipsilateral asynergia (disordered movements)
• Speech disturbances

Errors in distance of movements

tremor occuring during attempted movement

Difficulty in repetivite agonistic/antagonistic movements

Difficulty in forming spoken words

Irregular fluctuations in volume and rate