headpiece vs medulla oblongata

headpiece

noun
  • The head; the brain. 

  • A headstall. 

  • A decorative page heading used at the start of volumes or chapters. 

  • A headset. 

  • The top piece or part of various things. 

  • Something covering the head. 

  • Protecting cover for the head; a helmet. 

medulla oblongata

noun
  • The lower portion of the brainstem. 

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