Although only about 1/9 the volume of the cerebrum, the cerebellum (Latin for “little brain”) actually contains more brain cells than the cerebrum. The function of the cerebellum has traditionally been described as related to motor control, but it is now commonly accepted that the cerebellum is also involved in emotional processing and other higher cognitive functions that mature throughout adolescence (Riva and Giorgi 2000; Schmahmann 2004, 2010). Similarly to the cerebrum, the cerebellum is made up of subunits that arise from different embryologic precursors and appear to have evolved at different times. In cross section the anatomy of the cerebellum resembles a butterfly shape with the central body part corresponding to the cerebellar vermis and the wings corresponding to more recently evolved cerebellar hemispheric lobes. Developmental curves of total cerebellum size follow an inverted U shaped developmental trajectory with peak size occurring at 11.3 in girls and 15.6 in boys, similar to the cerebrum. However, these different subregions appear to follow different developmental trajectories. In contrast to the evolutionarily more recent cerebellar hemispheric lobes that followed the inverted U
