The Thorax

The rib cage consists of 12 pairs of ribs. These ribs form the walls of the thoracic cavity or thorax. Each pair of ribs joins onto a throracic vertebra posteriorly

The first 7 pairs attach directly onto the front of the sternum (breastbone) via costal cartilage (forming a cartilaginous joint between the sternum and ribs, (facilitating breathing).

The next 3 pairs are attached to the seventh rib, again via costal cartilage. These are known as ‘false ribs’.

The lower two pairs are not attached to anything at the front – only the thoracic vertebrae behind. These are known as ‘floating ribs’.

ribcageClick to enlarge

The rib cage helps to protect many vital organs such as the heart and lungs. It also enables the lungs to inflate by moving upwards and outwards during inspiration.

The ribs are attached to each other via intercostal muscles. These muscles allow the rib cage to carry out its respiratory role. During exercise, the internal intercostals contract and help to pull the ribcage downwards. This increases the individual’s breathing rate and also increases the amount of oxygen and carbon dioxide that can be exchanged in the lungs.

This, in turn, ensures that there is an adequate delivery of oxygen to the working muscles and removal of carbon dioxide and other metabolites (such as lactic acid).