CEREBELLUM

Gross Morphology Tentorium cerebelli Tentorium cerebelli Falx cerebelli Falx cerebelli

Anatomical Plan I Left and right hemispheres: Left and right hemispheres: Anterior and posterior lobe: Subconscious movements of skeletal muscles Flocculonodular nodes: Concerned with equilibrium Vermis Vermis

Anatomical Divisions Cerebellar cortex: Cerebellar cortex: Gyri = Folia Myelinated medulla: Myelinated medulla: Arbor vitae

Cerebellar Peduncles Inferior (restiform bodies): Inferior (restiform bodies): Connects to medulla Middle (brachium pontis): Middle (brachium pontis): Connects to pons Superior (brachium conjunctivum): Superior (brachium conjunctivum): Connects to midbrain and thalamus

Nuclei Intracerebellar (paired): Intracerebellar (paired):DentateEmboliformGloboseFastigial Pontine nuclei (pons): Pontine nuclei (pons): Inferior olivary nuclei (medulla) Inferior olivary nuclei (medulla)

Plan II: Flocculonodular Lobes Archicerebellum Archicerebellum Vestibulocerebellum Vestibulocerebellum Flocculi separated by nodulus Flocculi separated by nodulus Functions: Functions: Regulation of muscle tone Maintenance of equilibrium (axial musculature) Regulation of head/eye movements

Plan II: Anterior Lobe Paleocerebellum Paleocerebellum Functions: Functions: Receives proprioceptive information Regulates muscle tone

Plan II: Posterior Lobe Neocerebellum Neocerebellum Cerebrocerebellum Cerebrocerebellum Functions: Functions: Receives cerebral input via pons Involved in muscle movement Involved in planning and coordination

Anatomical Plan III Medial (vermal) zone: Medial (vermal) zone: Fastigial nucleus Part of spinocerebellum Paramedian (paravermal) zone: Paramedian (paravermal) zone: Globose and emboliform nuclei Part of spinocerebellum Lateral (hemispheric) zone: Lateral (hemispheric) zone: Dentate nucleus Equivalent to neocerebellum (cerebrocerebellum)

Afferent: Mossy Fibers Via inferior cerebellar peduncles: Via inferior cerebellar peduncles: Dorsal spinocerebellar Reticulocerebellar Via superior cerebellar peduncles: Via superior cerebellar peduncles: Ventral spinocerebellar Via middle cerebellar peduncles: Via middle cerebellar peduncles:Pontocerebellar

Afferent: Climbing Fibers Climbing fibers arise from inferior olivary nuclei Climbing fibers arise from inferior olivary nuclei

Efferent Tracts All efferent fibers from cortex are from Purkinje cells: All efferent fibers from cortex are from Purkinje cells: Purkinje cells project to intracerebellar nuclei. Purkinje cells project to intracerebellar nuclei.

Efferent Tracts Via inferior cerebellar peduncles: Via inferior cerebellar peduncles: To vestibular nuclei: Cerebellovestibular: From flocculonodular lobe = (vestibulocerebellum) From fastigial nucleus To lateral vestibular nucleus: Cerebellovestibular From anterior vermis (spinocerebellum)

Efferent Tracts Via inferior cerebellar peduncles: Via inferior cerebellar peduncles: To reticular formations in pons and medulla: Cerebelloreticular tract: From fastigial nucleus

Efferent Tracts Via superior cerebellar peduncles: Via superior cerebellar peduncles: To red nucleus (nucleus ruber): Cerebellorubral tract: From dentate, emboliform, and globose nuclei To ventral anterior and ventral lateral thalamic nuclei: Cerebellothalamic tracts: From dentate, emboliform, and globose nuclei

Efferent Tracts Thalamocortical tracts: Thalamocortical tracts: To motor cortex Through internal capsule Corticopontine tracts: Corticopontine tracts: To pontine nuclei

Functions Skeletal muscle coordination Skeletal muscle coordination Maintain equilibrium and posture Maintain equilibrium and posture Synergic control of muscle activity Synergic control of muscle activity Kinetic memory? Kinetic memory?

Cerebellar Cortex: Layers Molecular layer (outer) Molecular layer (outer) Granular layer (middle) Granular layer (middle) Purkinje layer (deeper) Purkinje layer (deeper)

Cerebellar Cortex: Cell Types Stellate cells Stellate cells Basket cells Basket cells Granular cells Granular cells Golgi cells Golgi cells Purkinje cells Purkinje cells

Cerebellar Cortex Organization Climbing and mossy fibers convey excitatory input from spinal cord and brainstem to deep cerebellar nuclei and cortex. Climbing and mossy fibers convey excitatory input from spinal cord and brainstem to deep cerebellar nuclei and cortex.

Cerebellar Cortex Organization Climbing fibers originate from inferior olivary nuclei and are excitatory to deep cerebellar nuclei and Purkinje cells. Climbing fibers originate from inferior olivary nuclei and are excitatory to deep cerebellar nuclei and Purkinje cells.

Cerebellar Cortex Organization Mossy fibers originate from spinal cord and other parts of the brain and are excitatory to granular cells. Mossy fibers originate from spinal cord and other parts of the brain and are excitatory to granular cells.

Granular Cells Granular cells receive input from mossy fibers: Granular cells receive input from mossy fibers: Excitatory input. Collaterals from mossy fibers also to intracerebellar nuclei. Granular cells project into molecular layer and give off left/right axon collaterals. Granular cells project into molecular layer and give off left/right axon collaterals.

Granular Cells Granular cells are excitatory. Granular cells are excitatory. Synapse with: Synapse with: Stellate, Golgi, basket, and Purkinje cells

Other Cortical Cells Stellate cells synapse with dendritic tree of Purkinje cells (inhibitory). Stellate cells synapse with dendritic tree of Purkinje cells (inhibitory). Basket cells synapse with axon hillock of Purkinje cell (inhibitory). Basket cells synapse with axon hillock of Purkinje cell (inhibitory). Golgi cells synapse with cell bodies of granular cells (inhibitory). Golgi cells synapse with cell bodies of granular cells (inhibitory). Purkinje cells synapse with intracerebellar nuclei (inhibitory). Purkinje cells synapse with intracerebellar nuclei (inhibitory).

Cerebellar Cortex Climbing fibers from inferior olivary nuclei: Climbing fibers from inferior olivary nuclei: Synapse with intracerebellar nuclei: Axon collaterals Excitatory Synapse with dendritic tree of Purkinje cells: Excitatory Excitatory burst “cleans” Purkinje cells

Cerebellar Cortex Only efferents from cerebellar cortex are Purkinje cell axons. Only efferents from cerebellar cortex are Purkinje cell axons. All efferents from cerebellum are from intracerebellar nuclei. All efferents from cerebellum are from intracerebellar nuclei.

Cerebellar Cortex Noradrenergic projections from locus ceruleus. Noradrenergic projections from locus ceruleus. Serotoninergic projections from raphe nuclei. Serotoninergic projections from raphe nuclei.