Anatomy of the cerebellum to describe the cellular structure is to begin with the inputs and follow the sequence of connections through to the outputs. The four deep nuclei of the cerebellum are the dentate, emboliform, globose, and fastigii nuclei and they act as the main centers of communication, sending and receiving information to and from specific parts of the brain. In addition, these nuclei receive both inhibitory and excitatory signals from other parts of the brain which in turn affect the nuclei's outgoing signals.(The globose and the emboliform nuclei make up the interposed nucleus). The cytoarchitecture (cellular organization) of the cerebellum is highly
Medulla (hair) Medulla (hair) The medulla is the innermost layer of the hair shaft. This nearly invisible layer is the most soft and fragile, and serves as the pith or marrow of the hair. Scientists are still uncertain about the exact role of the medulla, but they speculate that it is primarily an extension that is more prominent in depigmented (grey or white) hair Human hair is unique in that its medullary index (the fraction of the hair shaft's diameter that the medulla occupies) is very small: generally less than 1/3. Other species will have much larger ratios, usually at least 1/2.