cerebrum vs medulla oblongata

cerebrum

noun
  • The principal and most anterior part of the brain in vertebrates, which is located in the front area of the skull and divided into two hemispheres, left and right, separated by a fissure. In humans it is the largest part of the brain and is responsible for the integration of complex sensory functions and the initiation and coordination of voluntary activity, and the higher mental functions such as consciousness, thought, reason, emotion, and memory. 

medulla oblongata

noun
  • The lower portion of the brainstem. 

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