Acute pancreatitis causes severe upper abdominal pain that radiates to the back ... connecting muscles. These include conditions include: Monitoring pain under the left rib cage is important.

Your intercostal muscles between your ribs tightened up, too. This made your rib cage move up and out. Now breathe out. Your diaphragm loosened up and moved back up into your chest cavity.

Then there's the rib cage and sternum, which protect the heart and lungs. Besides protecting our organs, bones also work together with muscles and tendons to get the body moving. For example ...