The line at “Q” is pointing to the structure of the thoracic…

The line at “Q” is pointing to the structure of the thoracic cage called the _______ , which is made up of 3 bones.  The line at “M” is pointing to a _______ (use two words here-be specific and don’t use a number like rib 12).  And the line at “P” is pointing to  _______ of true ribs