astragalus vs instep

astragalus

noun
  • The anklebone. 

  • A herb of the genus Astragalus. 

instep

noun
  • The arched part of the top of the foot between the toes and the ankle. 

  • In horses, the hind leg from the ham to the pastern joint. 

  • A section of any footwear covering that part of the foot. 

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