Why does my chest bone hurt?

Why do the bone in the middle of my chest hurt?

• when i was sitting on my chair i arched backward (kind of like looking back) then all of a sudden i heard a crack and when i went back into a normal sitting position, i exhale and there's a sharp pain in the middle of my chest =( (I'm only 17) should i be worried about this? because the pain goes away later on

• Answer:

  The bone in the middle of your chest is called the sternum, and connects your ribcage together, so it acts as a joint. It can crack and hurt if you stretch it too far. I wouldn't worry about it, unless it happens often or the pain doesn't go away.