bone marrow vs marrowbone

bone marrow

noun
  • The fatty vascular tissue that fills the cavities of bones, being the place where new blood cells are produced. 

marrowbone

noun
  • A bone containing edible marrow. 

  • The shins or knees, chiefly in references to kneeling. 

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