The current anatomical concept of the projections from the cerebellar cortex to the cerebellar nuclei stems from the classical work of Jansen and Brodal. They demonstrated that the cerebellar cortex is arranged in three longitudinal zones: medial, intermediate, and lateral. Fibers from these zones project ipsilaterally to the fastigial, interpositus, and lateral (dentate) nuclei, respectively. Subsequent physiological investigations have provided strong confirmation of this anatomical concept. However, several recent anatomical studies have shown that there are many exceptions to this projection pattern. Thus, a single zone may apparently project to more than one nucleus and, conversely, a single nucleus may apparently receive fibers from more zones than one. In 1964, Voogd explained these exceptions by proposing that the concept of a projection zone sending fibers to one central nucleus should be retained, but the three zones and central nuclei must be further differentiated into multiple zones and nuclei.
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