The human thoracic region (rib cage) consists of twenty four ribs (Fig 2). The ribs are thin flat, curved bones divided into three categories:
- The true ribs (seven pair) connect in the back to the spine and in front to the sternum.
- The false ribs (three pair) connect in back to spine and to the lowest true rib.
- The floating ribs (two pair) connect in back to the spine but have no attachment in front.
The costal cartilage is hyaline cartilage that extends the ribs to the sternum and adds to the elasticity of the walls of the thorax (rib cage).