cerebellum. Functional Anatomy . cerebellum. ‘little brain’ 10% of brain mass As many neurons as the rest of the CNS Every kind of sensory input reaches the cerebellar cortex, which projects via deep cerebellar nuclei to various sites in brain stem and thalamus
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Motor part of the brain, serving to maintain equilibrium and coordinate muscle contractions.
Ensures that contraction of the proper muscles occurs at the appropriate time, each with the correct force.
Imagined movements are accompanied by an increase in cerebellar blood flow that is larger than the increase detected in the motor areas of the cerebral cortex.
The cerebellum consists of a cortex, or surface layer, of gray matter contained in transverse folds or folia plus a central body of white matter.
The Pontocerebellum/cerebrocerebellum comprises the large lateral parts of the hemispheres and the superior vermis in the posterior lobe; afferents are from the contralateralpontine nuclei.
The interposed nucleus (comprising two cell clusters, the globose and the emboliform nuclei) is situated between the fastigial and dentate nuclei.
Its efferent fibers occupy the interior of the nucleus and leave through the hilus.
Whereas the input to the central nuclei from outside the cerebellum is excitatory, the input from Purkinje cells, which use GABA as their transmitter, is inhibitory.
combination of the two inputs maintains a tonic discharge from the central nuclei to
the brain stem and thalamus.
Hemisphere divided into a medial part= intermediate/paravermal zone
The pontocerebellum comprises the large lateral parts of the hemispheres and the superior vermis in the posterior lobe
Fibers from the cortex and the fastigial nucleus traverse the inferior cerebellar peduncle to their termination in the vestibular nuclear complex and in the central group of reticular nuclei
The posterior vermis also contributes to the cerebellar control of eye movements.
INFERIOR OLIVARY COMPLEX- accessory olivary nuclei [olivospinal tracts end here]. Olivocerebellarfibres end as climbing fibres in cortex
Axons from the interposed nuclei traverse the superior cerebellar peduncle and terminate in the central group of reticular nuclei.
Alpha and gamma motor neurons are involved in cerebellar control of muscle action, and the influence of the spinocerebellum on the skeletal musculature is ipsilateral.
Some axons from the interposed nuclei traverse the superior cerebellar peduncle and end in the red nucleus, which, in turn, projects to the inferior olivary nucleus.
Motor neurons are influenced mainly through relays in the vestibular nuclei, the reticular formation, and the primary motor area of the cerebral cortex.
The corticopontine tracts originate in widespread areas of the contralateral cerebral cortex (especially that of the frontal and parietal lobes but also temporal and occipital) and end in the pontine nuclei
Through the corticopontine and pontocerebellar projections, the cortex of a cerebellar hemisphere receives information concerning volitional movements that are anticipated or in progress.
the superior vermis of the posterior lobe, similar to the spinocerebellar cortex, receives tectocerebellar fibers from the superior and inferior colliculi.
In turn, this thalamic nucleus projects to the primary motor area of cerebral cortex in the frontal lobe.