The ribcage is a part of the skeleton of humans and some animals. It is made up of curved bones. The rib cage is found in the chest area. It protects a persons 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, full of calcium and protein.