Rib cage
The rib cage is the arrangement of ribs attached to the vertebral column and sternum in the thorax of most vertebrates, that encloses and protects the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdle to form the core part of the human skeleton. A typical human rib cage consists of 24 ribs in 12 pairs, the sternum and xiphoid process, the costal cartilages, and the 12 thoracic vertebrae.
Pump handle movement
One of the most important functions of the ribs and diaphragm is the change in volume of the thorax that helps inspiration and expiration. In general, the ribs move around two axes. The anterior end of the rib is lower than the posterior end; therefore, during elevation of the rib, the anterior end also moves forwards. Movement at costovertebral joints 2 to 6 about a side-to-side axis results in raising and lowering the sternal end of the rib, the "pump-handle" movement.This occurs mostly in the vertebrosternal ribs. In elevation, this increases the anteroposterior diameter of the thorax.