thorax vs upper trunk

thorax

noun
  • The middle of three distinct divisions in an insect, crustacean or arachnid body to which the legs are attached. 

  • The region of the mammalian body between the neck and abdomen as well as the cavity containing the heart and lungs. 

upper trunk

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