Costal cartilages

At a glance

English

Costal cartilages

Latin (TA2)

Cartilagines costales

System

Cartilage

Region

Thorax

In order

From the costal cartilage of first rib to the costal cartilage of tenth rib

About the costal cartilages

The costal cartilages are bars of hyaline cartilage that continue the ribs at the front of the chest. Each one is joined end to end to the front tip of its rib at a costochondral junction, where the bone of the rib is cupped around the cartilage with no joint cavity between them. Medially the cartilages either reach the sternum or end on the cartilage above. They give the thoracic cage the flexibility it needs to widen and narrow with every breath and to absorb blows to the front of the chest.

The members share a simple build: a flattened bar with an anterior surface facing the skin and pectoral muscles, a posterior surface facing the inside of the chest, and upper and lower borders that give attachment to the internal and external intercostal membranes and muscles. Behind them run the internal thoracic vessels, and transversus thoracis arises from the inner surfaces of the lower ones. Their perichondrium continues with the periosteum of the rib and the sternum.

Along the series the cartilages change in length, direction and the way they end. The first is short and broad and joins the manubrium by a primary cartilaginous joint without a cavity. The second to seventh meet the sternum at synovial sternocostal joints; the second fits into the notch at the sternal angle, opposite the manubriosternal joint, a useful landmark for counting ribs. Their length increases from the first to the seventh, and from the third onwards they slope increasingly upwards and medially from the rib end. The eighth, ninth and tenth do not reach the sternum. Each passes up to join the lower border of the cartilage above, building the curved costal margin that frames the upper abdomen; adjacent cartilages from the sixth to the ninth also touch each other at small interchondral joints. The eleventh and twelfth ribs have only tiny pointed caps of cartilage that end free in the muscles of the flank, so they are not counted in this series.

With age the cartilages often calcify or partly ossify, first at the edges and in the core. The process makes the chest stiffer and shows on plain radiographs as patchy shadows that should not be mistaken for disease. Painful swelling of the upper cartilages near the sternum is called costochondritis or, when swelling is obvious, Tietze syndrome. The cartilages are also a source of graft material for reconstructive surgery of the nose and ear, and the eighth to tenth may slip and click against each other, causing pain at the costal margin.