COORDINATION

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