A region of the brain behind the brainstem concerned with maintaining posture and balance and coordinating movement.
The cerebellum is situated behind the brainstem and has 2 hemispheres.
From the inner side of each hemisphere arise 3 nerve fibre stalks, which link up with different parts of the brainstem and carry signals between the cerebellum and the rest of the brain.
Nerve fibres from these stalks fan out towards the deep folds of the cortex (outer part) of each brain hemisphere, which consists of layers of grey matter.
Information about the body’s posture and the state of contraction or relaxation in its muscles is conveyed from muscle tendons and the labyrinth in the inner ear via the brainstem to the cerebellum.
Working with the basal ganglia (nerve cell clusters deep within the brain), the cerebellum uses this data to fine tune messages sent to muscles from the motor cortex in the cerebrum.
n. the largest part of the hindbrain, bulging back behind the pons and the medulla oblongata and overhung by the occipital lobes of the cerebrum. Like the cerebrum, it has an outer grey cortex and a core of white matter. Three broad bands of nerve fibres – the inferior, middle, and superior cerebellar peduncles – connect it to the medulla, the pons, and the midbrain respectively. It has two hemispheres, one on each side of the central region (the vermis), and its surface is thrown into thin folds called folia (see illustration). Within lie four pairs of nuclei.
The cerebellum is essential for the maintenance of muscle tone, balance, and the synchronization of activity in groups of muscles under voluntary control, converting muscular contractions into smooth coordinated movement. It does not, however, initiate movement and plays no part in the perception of conscious sensations or in intelligence. —cerebellar adj.
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