Cerebellum as center of coordination
- Anatomy
- Physiology
- Its disorder
Anatomy
• Occupies most of the posterior cranial fossa
• Dorsal to the brainstem and attached to it by cerebellar peduncles :
– Superior cerebellar peduncle (Brachium conjunctivum) « midbrain
– Middle cerebellar peduncle (Brachium pontis) « pons
– Inferior cerebellar peduncle (restiform body) « medulla oblongata
• Other relationship :
– The fourth ventricle
– Tentorium cerebelli
• Composition
– Cerebellar hemispheres
– Vermis : cortex and medulla (incl. Nuclei)
• Lobes
– Anterior lobe (palaocerebellum)
• C/o most of the vermis and anterior aspect of hemispheres
• Associated with proprioceptive (spinecerebellar) and exteroceptive input
• Significant role in regulation of muscle tone (maintain posture)
– Posterior lobe (neocerebellum)
• The largest part; c/o main bulk of hemisphere and part of vermis
• Receive connections of cerebrum through nuclei & brachium pontis
• Role in muscular coordiantion of phasic movement
– Flocculonodular lobe (archicerebellum)
• C/o paired flocculi of hemispheres and unpaired nodulus
• Cerebellar portion of vestibular system (somatic afferent collumn)
• Significant role in muscle tone, equilibrium, and posture (trunk muscles)
Cerebellar cortex
• Layers
– Molecular layer :
• Outer layer – synaptic integrative layer
• Input from granular layer and deep cerebellar nuclei
• C/o nerve fibers and some basket cell
– Purkinje cell layer
• Middle cell layer –Output layer to the intrinsic cerebellar nuclei
– Granular layer
• Innermost layer – receive input from outside
• Cell and Nerve types
