flexion vs intorsion

flexion

noun
  • The state of being bent or flexed. 

  • Deviation from straightness. 

  • The act of bending a joint, especially a bone joint; the counteraction of extension. 

intorsion

noun
  • A winding, bending, or twisting. 

  • The bending or twining of any part of a plant toward one side or the other, or in any direction from the vertical. 

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