bowels vs rib cage

bowels

noun
  • The intestines. 

  • The concept or quality that defines something at its very core. 

  • The deepest or innermost part. 

  • Compassion, sympathy. 

rib cage

noun
  • The enclosed area created by and within the ribs. 

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

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