A simple fracture of a rib is usually caused by a direct blow to the chest or by compression of the chest.

The casualty usually has local pain at the site of the fracture and the pain is usually aggravated when he breathes or moves. There may be a bruise or swelling at the fracture site. The most common fracture sites are the fifth to the tenth pair of ribs. The upper pairs of ribs are protected by the bones of the shoulders. The lower (eleventh and twelfth) pairs of ribs are not attached to the sternum and have greater flexibility.