Question: What is the function of the rib cage in gas exchange in detail please?  Edit

Answer: Rib cage movements are controlled by two sets of muscles - external intercostal muscles that are found between ribs running downward towards the sternum and internal intercostal muscles found between ribs running at right angle to the external intercostal muscles.

During expiration, internal intercostal muscles get contracted and the external muscles relax. The rib cage is then raised inwards and downwards.

During inspiration, external muscles contract while the internal intercostal muscles relax. This time, the rib cage is raised upwards and outwards.  Edit