One of the most important functions of ribs and diaphragm is the change in volume of thorax that helps inspiration and expiration.[2] In general, the ribs move around two axes.[3] As the anterior end of ribs is about 4 cm lower than the posterior end, the middle part of rib is lower than anterior and posterior ends. Movement at costovertebral joints 7 to 10 about an anteroposterior axis results in raising and lowering the middle of the rib, the Bucket-handle movement. In elevation, this increases the transverse diameter of the thorax.[3][4]