instep vs planta

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. 

planta

noun
  • The sole of the foot 

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