• basal
  • These simple, early vesicles enlarge and further divide into the telencephalon (future cerebral cortex and basal ganglia), diencephalon (future thalamus and hypothalamus), mesencephalon (future colliculi), metencephalon (future pons and cerebellum), and myelencephalon (future medulla). (wikipedia.org)
  • primary
  • As early as the 1950s, the spiral ganglion was proposed to play the primary role in the ability to understand speech, leading to the development of the cochlear implant, which is arguably the most clinically successful biotechnological implant available in any field. (lww.com)