incus vs middle ear

incus

noun
  • A small anvil-shaped bone in the middle ear. 

  • an accessory cloud, in the shape of an anvil which forms by spreading at the top of a cumulonimbus. 

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. 

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