Revision as of 01:14, 17 June 2015

Cerebellum

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Divisions

Cerebellum consists of:

• Fastigial Nucleus
• Globose Nucleus
• Emboliform Nucleus
• Dentate Nucleus
• Cerebellum Cortex
• Interposed Nucleus = Globose Nucleus + Emboliform Nucleus

Diagrams

Neurons:

Connections:

Cerebellum Cortex

Cerebellum Cortex consists of:

• Medial=Vermal (projects to Fastigial Nucleus)
• Intermediate=Paravermal (projects to Interposed Nucleus)
• Lateral=Hemisphere (projects to Dentate Nucleus)

Cerebellum Lobes:

• Archicerebellum=Vestibulocerebellum (vermis) - vestibular->body
• Paleocerebellum=Spinocerebellum (vermal, paravermal) - body->body
• Neocerebellum (posterior) - cerebral cortex->body

Cortex Layers:

• Molecular layer (outer)
• Purkinje cell layer
• Granular layer

Cerebellum Neurons

• granular cells (total 100G) - like "T"
  • 4-6 short dendrites
  • axon goes to molecular layer and bifurcates into 2 branches
  • branches go in opposite directions
  • branches have excitatory synapses with Purkinje cells dendrites
• Purkinje cell - the only output of CR
  • each Purkinje cell receives synapses from thousands of parallel fibers
  • Purkinje cell projects to CR nuclei as inhibitory
  • recurrent axon collaterals have inhibitory connections with other Purkinje cells
• cerebellum nuclei exert excitary influences on muscles

Cerebellum Inputs

Climbing Fibers:

• arrive from inferior olivary nucleus
• excitatory to cerebellum cortex Purkinje cells
• excitatory to cerebellum nuclei
• each fiber divides into 10 branches within granular layer
• branches go to molecular layer and synapse with Purkinje cells
• each branch has several hundreds of synapses
• one branch contacts several Purkinje cells
• one Purkinje cell receives input from only one climbing fiber

Mossy Fibers:

• originate from SC, vestibular, trigeminal, pontine, bRF
• excitatory to granule cells
• excitatory to cerebellum nuclei

Raphe Nucleus:

• to cerebellar nuclei
• to cerebellar cortex

Locus Ceruleus:

• to Purkinje cells