11. Impact Biomechanics of the Thorax

The thorax occupies the upper part of the torso and contains the lung and heart that are enclosed by a rib cage. Of course, the lung, heart, and the great vessels are vital organs that need to be protected from external forces but the enclosure also needs to be expandable to assist in the respiratory function. The rib cage is capable of expanding the thorax and can provide some protection to the thoracic organs. However, for high speed impacts, the ribs are vulnerable to fracture. Although multiple rib fractures are serious injuries, the fracture of a rib or two is relatively minor. But, when cadavers are used to assess thoracic injury, rib fracture is the only measure because injuries to the heart and lung are generally not assessable in dead tissue. Because of the variability in human tolerance, the number of rib fractures and the number of fractured ribs cannot be correlated to the severity of injuries to the thoracic organs.