middle ear vs tympanic cavity

middle ear

noun
  • The cavity in the temporal bone between the eardrum and the inner ear that contains the ossicles, and which conveys sound to the cochlea. 

tympanic cavity

noun
  • A small cavity surrounding the bones of the middle ear. 

How often have the words middle ear and tympanic cavity occurred in a corpus of books? (source: Google Ngram Viewer )