bending vs flexion

bending

noun
  • A motion or action that bends. 

  • An instance of something being adapted or distorted. 

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. 

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