Anatomy of the cerebellum a narrow midline zone called the "vermis". A set of large folds are conventionally used to divide the overall structure into ten smaller lobules. Because of its large number of tiny granule cells, the cerebellum contains more neurons than the rest of the brain put together, but it only takes up 10% of total brain volume. The cerebellum receives nearly 200 million input fibers; in contrast, the optic nerve is composed of a mere one million fibers. The unusual surface appearance of the cerebellum conceals the fact that the bulk of the structure is made up of a very tightly
Anatomy of the cerebellum the numerous and tiny granule cells, the slightly larger unipolar brush cells and the much larger Golgi cells. Mossy fibers enter the granular layer from their main point of origin, the pontine nuclei. These fibers form excitatory synapses with the granule cells and the cells of the deep cerebellar nuclei. The granule cells send their T-shaped axons—known as parallel fibers—up into the superficial molecular layer, where they form hundreds of thousands of synapses with Purkinje cell dendrites. The human cerebellum contains on the order of 60 to 80 billion granule cells, making this single cell type by far the most