Rib cage pain can be caused by a variety of things, ranging from pulled muscles to a rib fracture. The pain may occur immediately upon injury or develop slowly over time. It can also be a sign of an underlying medical condition. 3 Reasons You Might Have Rib Cage Pain: 1. Bruised or fractured rib. Your rib cage provides a crucial function: to protect your heart, lungs and other vital organs. But this may also mean they take the brunt of the damage in the case of trauma, such as a car accident, st