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Questions and Answers
What is the primary function of commissural fibres in the cerebellum?
What is the primary function of commissural fibres in the cerebellum?
Which type of fibres exclusively connects the cerebellum with the brain and spinal cord?
Which type of fibres exclusively connects the cerebellum with the brain and spinal cord?
What is the term for the thin lamina of fibres that connects the white matter of the two sides of the cerebellum?
What is the term for the thin lamina of fibres that connects the white matter of the two sides of the cerebellum?
Which type of fibres is responsible for connecting the cerebellar cortex to the cerebellar nuclei?
Which type of fibres is responsible for connecting the cerebellar cortex to the cerebellar nuclei?
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What is the term for the three thick bundles of fibres that connect the cerebellum with other parts of the central nervous system?
What is the term for the three thick bundles of fibres that connect the cerebellum with other parts of the central nervous system?
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What is the primary location where mossy fibres terminate in the cerebellar cortex?
What is the primary location where mossy fibres terminate in the cerebellar cortex?
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What is the primary function of axons of Purkinje cells in the cerebellar nuclei?
What is the primary function of axons of Purkinje cells in the cerebellar nuclei?
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Which of the following nuclei is considered a displaced cerebellar nucleus?
Which of the following nuclei is considered a displaced cerebellar nucleus?
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What is the primary output pathway from the cerebellum to the cerebral cortex?
What is the primary output pathway from the cerebellum to the cerebral cortex?
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What is the primary source of integrative input to the cerebellum?
What is the primary source of integrative input to the cerebellum?
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Study Notes
White Matter and Fibres of the Cerebellum
- The white matter of the two sides of the cerebellum is connected by a thin lamina of fibres related to the fourth ventricle.
- The upper part of this lamina forms the superior medullary velum, and its lower part forms two crescentic sheets called inferior medullary vela.
- Both the superior medullary velum and inferior medullary vela take part in the formation of the roof of the fourth ventricle.
Types of Fibres
- The white matter consists of two types of fibres: intrinsic and extrinsic fibres.
Intrinsic Fibres
- Intrinsic fibres remain confined within the cerebellum.
- They connect different regions of the cerebellum either in the same hemisphere or between the two cerebellar hemispheres.
- There are three types of intrinsic fibres:
- Projection fibres: connect the cerebellar cortex to the cerebellar nuclei.
- Association fibres: interconnect different parts of the cerebellar cortex.
- Commissural fibres: connect the two cerebellar hemispheres.
Extrinsic Fibres
- Extrinsic fibres connect the cerebellum with other parts of the central nervous system, including the brain and spinal cord.
- These fibres pass through three thick bundles called the cerebellar peduncles: superior, middle, and inferior.
Afferent Fibres
- Afferent fibres are of two types: mossy fibres and climbing fibres.
- Mossy fibres:
- Originate from the vestibular nuclei, pontine nuclei, and spinal cord.
- Terminate in the granular layer of the cortex within the glomeruli.
- Pass through granule cells to reach Purkinje cells.
- Climbing fibres:
- Represent terminations of axons from the inferior olivary complex.
- Pass through the granular layer and Purkinje cell layer to reach the molecular layer.
- Each climbing fibre becomes intimately associated with the proximal part of the dendritic tree of one Purkinje cell.
Efferent Fibres
- Efferent fibres are axons of Purkinje cells, which terminate in the cerebellar (central) nuclei.
- Some efferents from the flocculonodular lobe bypass the cerebellar nuclei and terminate in the brainstem nuclei.
- Axons of Purkinje cells are inhibitory to cerebellar nuclei.
Connections of the Cerebellum
- Afferent fibres terminate in the cortex.
- Efferent fibres arising in the cortex end in cerebellar nuclei.
- Fibres arising in the nuclei project to centres outside the cerebellum.
- The main afferent inputs to the cerebellum are proprioception, exteroception, vision, and from the vestibular apparatus.
- The main efferents from the cerebellum go via the thalamus to the cerebral cortex.
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Description
Test your knowledge of cerebellum anatomy, including the connection of white matter, medullary vela, and fibre types. Learn about the intrinsic and extrinsic fibres and their functions in the cerebellum.
