Internal features :
Cerebellar Cortex : is the outer layer
- Plays a crucial role in motor coordination, balance, and motor learning.
- Organized into distinct layers:
- Molecular Layer (Outermost) : Contains axon branches of granule cells & the dendrites of Purkinje cells. → Stellate + Basket cells.
- Purkinje cell layer : Receiving 2 types of afferent fibers (direct climbing : from olivary nuclei) and (indirect Mossy : the remaining afferent fibers after relay in granule cells).
- 3. Granular layer : - the innermost layer. - Contains granular cells. + Golgi cells
3. Cerebellar white matter:
- Superior Cerebellar Peduncle: Primarily efferent fibers that project to the midbrain and thalamus.
- Middle Cerebellar Peduncle: Contains afferent fibers from the pons (pontocerebellar fibers) that carry input from the cerebral cortex.
- Inferior Cerebellar Peduncle: Contains both afferent and efferent fibers, connecting the cerebellum with the medulla and spinal cord.
2. Cerebellar nuclei
- They are embedded within the white matter.
- They are :
- 1. Fastigial nucleus; medially → flocculonodular lobe + vermis
- 2. Dentate nucleus ; laterally → lateral hemisphere
- 3. Interposed nuclei ; in between: → vermal + paravermal areas globose & emboliform nuclei
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4. Fiber types
- Climbing Fibers: Originate from the inferior olivary nucleus and make powerful excitatory synapses with Purkinje cells.
- Mossy Fibers: Originate from various sources including the spinal cord, pontine nuclei, and vestibular system. They synapse with granule cells in the granule cell layer, indirectly influencing Purkinje cells through parallel fibers.