rib cage vs thorax

rib cage

noun
  • A part of the skeleton within the thoracic area consisting of ribs, sternum and thoracic vertebrae. 

  • The enclosed area created by and within the ribs. 

thorax

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

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

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