During exhalation the ribs move downwards and inwards.
What is exhalation?
Exhalation is the act of exhaling air taken in and is passive. The diaphragm relaxes, moving upwards into the chest cavity. During exhalation, the diaphragm moves up and ribs move downwards and inwards, decreasing the space in the chest cavity, this increases the air pressure inside the lungs and forces the air out of the lungs. The intercostal muscles between the ribs relax, causing the area of the chest cavity to reduce. Eventually, the area in the chest reduces and carbon dioxide-rich air is expelled out of the lungs and windpipe, ultimately out of the nose