—cerebellar, adj./ser'euh bel"euhm/, n., pl. cerebellums, cerebella /-bel"euh/. Anat., Zool.a large portion of the brain, serving to coordinate voluntary movements, posture, and balance in humans, being in back of and below the cerebrum and consisting of two lateral lobes and a central lobe. See illus. under brain.
* * *Part of the brain that integrates sensory input from the inner ear and from proprioceptors (see proprioception) in muscle with nerve impulses from the cerebrum (see cerebral cortex), coordinating muscle responses to maintain balance and produce smooth, coordinated movements.Located below the cerebral hemispheres and behind the upper medulla oblongata and pons, each of its two connected hemispheres has a core of white matter within a cortex of gray matter. Disorders usually produce neuromuscular disturbances, in particular ataxia.
* * *▪ anatomysection of the brain that coordinates sensory input with muscular responses, located just below and behind the cerebral hemispheres and above the medulla oblongata.The cerebellum integrates nerve impulses from the labyrinths of the ear (ear, human) and from positional sensors in the muscles; cerebellar signals then determine the extent and timing of contraction of individual muscle fibres to make fine adjustments in maintaining balance and posture and to produce smooth, coordinated movements of large muscle masses in voluntary motions.Like the cerebrum, the cerebellum is divided into two lateral hemispheres, which are connected by a medial part called the vermis. Each of the hemispheres consists of a central core of white matter and a surface cortex of gray matter and is divided into three lobes. The flocculonodular lobe, the first section of cerebellum to evolve, receives sensory input from the vestibules of the ear; the anterior lobe receives sensory input from the spinal cord; and the posterior lobe, the last to evolve, receives nerve impulses from the cerebrum. All of these nerve impulses are integrated within the cerebellar cortex.Injuries or disease affecting the cerebellum usually produce neuromuscular disturbances, in particular ataxia, or disruptions of coordinated limb movements. The loss of integrated muscular control may cause tremors and difficulty in standing.
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