fauces vs lower jaw

fauces

noun
  • The narrow passage from the mouth to the pharynx, situated between the soft palate and the base of the tongue. 

  • That portion of the interior of a spiral shell which can be seen by looking into the aperture. 

  • The throat of a calyx, corolla, etc. 

lower jaw

noun
  • The part of the face below the mouth; the jaw. 

  • Specifically, the bone therein; the mandible of humans and other vertebrates that, with the cranium, composes the skull. 

How often have the words fauces and lower jaw occurred in a corpus of books? (source: Google Ngram Viewer )