The ossific centers appear in the intervals between the articular depressions for the coastal cartilages, in the following order: in the manubrium and first piece of the body, during the sixth month;...
I guess one could think of the sternum as the "backbone" that holds the ribs together, keeps them in place. The sternum and ribs are a cage like system that protects your heart and lungs from injury....
The sternum is a flat, dagger shaped bone located in the middle of the chest. Along with the ribs, the sternum forms the rib cage that protects the heart, lungs, and major blood vessels from damage....