cerebellum vs medulla oblongata

cerebellum

noun
  • Part of the hindbrain in vertebrates. In humans it lies between the brainstem and the back of the cerebrum and is formed of two lateral lobes and a median lobe. It plays an important role in sensory perception, motor output, balance and posture. 

medulla oblongata

noun
  • The lower portion of the brainstem. 

How often have the words cerebellum and medulla oblongata occurred in a corpus of books? (source: Google Ngram Viewer )