orifice vs pharynx

orifice

noun
  • A mouth or aperture, such as of a tube, pipe, etc.; an opening. 

pharynx

noun
  • The part of the alimentary canal immediately behind the mouth in invertebrates that may be thickened and muscular, eversible and toothed, or adapted as a suctorial organ. 

  • The part of the alimentary canal and respiratory tract that extends from the back of the mouth and nasal cavity to the larynx and esophagus. 

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