2.4 Cerebellum. Conduction Pathways. Signs of Lesions
Figure 2.7. Main cerebellar connections (J.D. Fix, 1994)
The cerebellum is a central organ for motor control. The main functions of the cerebellum are control of balance, posture, gait, and goal-directed movement, and the regulation of muscle tone. Cerebellum lies in the fossa posterior and has got two hemispheres and the vermis. It’s connected to the brain by the three cerebellar peduncles. In superior or inferior views, the shape of the cerebellum is like a butterfly. Each hemisphere consists of 3 lobes separated by deep and distinct fissures. The cerebellum has 3 functional parts:
Archicerebellum (vestibulocerebellum): The central area is the vermis (“worm”). It includes the flocculonodular lobe, which is located in the medial zone. It helps maintain equilibrium and coordinate eye, head, and neck movements; it is closely connected with the vestibular nuclei.
Midline vermis (paleocerebellum): It’s a lateral "wings" or lobes are the cerebellar hemispheres. It helps coordinate trunk and leg movements. Vermis lesions result in abnormalities of stance and gait.
Lateral hemispheres (neocerebellum): They control quick and finely coordinated limb movements, predominantly of the arms. Cerebellar cortex contains three layers:
The molecular layer contains stellate cells, basket cells, and the dendritic arbor of the Purkinje cells.
The Purkinje cell layer is found between the molecular and granule cell layers.
The granular layer is the inner layer overlying the white matter. It contains granule cells, Golgi cells, and cerebellar glomeruli.
