forearm vs ulna

forearm

noun
  • The part of the arm between the wrist and the elbow. 

  • A section of the weapon between the receiver and the muzzle, used to hold the firearm steady. 

verb
  • To arm in preparation. 

ulna

noun
  • The bone of the forearm that extends from the elbow to the wrist on the side opposite to the thumb, corresponding to the fibula of the hind limb. Also, the corresponding bone in the forelimb of any vertebrate. 

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