ankle vs mortise joint

ankle

noun
  • The skeletal joint which connects the foot with the leg; the uppermost portion of the foot and lowermost portion of the leg, which contain this skeletal joint. 

verb
  • To walk. 

  • To cyclically angle the foot at the ankle while pedaling, to maximize the amount of work applied to the pedal during each revolution. 

mortise joint

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