Final answer:
The cerebellar hemispheres are separated by the vermis, an integral part of the cerebellum's midline region, which plays a vital role in balance and movement coordination.
Step-by-step explanation:
The cerebellar hemispheres are separated by a band of cortex called the vermis. This structure is part of the midline region of the cerebellum, along with the flocculonodular lobe, and is involved in several functions related to balance and coordination of movements. The vermis receives proprioceptive input from the dorsal columns and spinocerebellar pathways and is thus referred to as the spinocerebellum. On the other hand, the flocculonodular lobe is involved in balance and equilibrium, receiving vestibular input, and is referred to as the vestibulocerebellum. The lateral hemispheres, which are to the sides of the vermis and flocculonodular lobe, are primarily concerned with planning motor functions, receiving significant frontal lobe inputs that are returned through thalamic projections to the premotor and motor cortices.