cubit vs elbow joint

cubit

noun
  • The distance from the elbow to the tip of the middle finger used as an informal unit of length. 

  • Any of various units of length approximating this distance, usually around 35–60 cm. 

elbow joint

noun
  • Synonym of elbow. 

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