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Brain Motor Centers and Pathways
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Based mainly on their sources of input and their projections, the cerebellar hemispheres can be divided into three major subdivisions: Vestibulocerebellum, comprising the flocculonodular lobe. Phylogenetically, this is the oldest part of the cerebellum, and which first appeared in fishes. It derives its input from the inner ear, or labyrinth, the visual system, and the somatosensory receptors of the neck, via the vestibulocerebellar, spinocerebellar, and pontocerebellar paths. The vestibulocerebellum is involved in the vestibulo-ocular reflex (Section 12.2.5.3), in the maintenance of balance and posture and in eye movements.Spinocerebellum, comprising the vermis and pars intermedia, and which appears later in phylogeny. The vermis receives somatosensory and proprioceptive inputs from the head and proximal parts of the body, as well as visual inputs, and auditory inputs via the inferior colliculus. All this information is conveyed via the vestibulocerebellar, spinocerebellar, and pontocerebellar paths. The spinocerebellum projects, via the fastigial nucleus, to the vestibular nuclei and the ventrolateral thalamus (VL) and is involved in the control of proximal muscles of the body and limbs, in locomotion, and in eye movements. The pars intermedia also receives somatosensory and proprioceptive inputs but from the limbs via the spinocerebellar nuclei, as well as inputs from the motor cortex via the pontine nuclei. It projects via the interposed nucleus to the red nucleus, the reticular nuclei, and the ventrolateral thalamus, and is involved in the control of the more distal muscles of the limbs and the digits.Cerebrocerebellum, comprising the pars lateralis and is phylogenetically the most recent. It is much enlarged in apes and even more so in humans, paralleling the evolutionary enlargement of the prefrontal cerebral cortex. It receives its inputs from the association areas of the motor cortex, the prefrontal lobe, and the parietal lobe via the pontine nuclei. It projects via the dentate nucleus to the red nucleus, the reticular nuclei, and the ventrolateral thalamus. It is involved in many functions including the timing of voluntary movements, the execution of complex spatial and temporal sequences of movement, including speech, as well as in learning of motor skills and in certain cognitive functions, as will be elaborated later (Section 12.2.4.5).
Computational RSM modelling of dentate nucleus neuron 2D image surface
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Ivan Grbatinić, Nemanja Rajković, Nebojša Milošević
The dentate nucleus occupies a central position in the cerebellar circuitry, serving as a relay centre for fibres coming from the cerebellar cortex, namely from the axons of Purkinje cells (Chan-Palay 1977). It represents the largest and phylogenetically most recent of the cerebellar white matter nuclei and plays an important role as a major relay centre between the cortex and the other parts of the brain. It receives its afferents from the premotor cortex and supplementary motor cortex (via the pontocerebellar system) and its efferents project via the superior cerebellar peduncle through the red nucleus to the ventrolateral thalamus (crossing over at the pontomesencephalic junction). It is responsible for the planning, initiation and control of volitional movements (Mathiak et al. 2002).