Explain the process of inspiration and the various muscles involved.

During inspiration the diaphragm contracts and flattens and the external intercostal muscles contract. This moves the rib cage up and out and increases the volume of the thorax. This reduces the pressure inside the lungs to below atmospheric and therefore air moves down a pressure gradient from the atmosphere and into the lungs ( high to low). ( I can also go through the reverse process of expiration if this is not long enough )