The ribcage is a part of the skeleton of humans and some animals. It is made up of curved bones called ribs. The rib cage is found in the chest area. It protects a person's internal organs from damage. Most humans have 12 pairs of rib bones with one from each pair on each side of the chest. Some people may have 11 or 13 pairs of rib bones. The bones are also filled with bone marrow. The bones that are connected to the sternum directly are called true ribs, and the bones that are connected to the sternum indirectly, through the seventh bone, are called false ribs (eighth, ninth, and tenth bones), and the bones which are not connected to the sternum, and is connected to the back bone, are called floating ribs. If these floating ribs were connected to the sternum, we could not breathe properly, as the chest needs space to expand and decrease. The rib cage is also called the thoracic cavity.