Inhalation is the process of air being drawn into the lungs. During the process of inhalation the external intercostal muscles contract, therefore pulling the chest wall upwards and outwards, these intercostal muscles are between the ribs. As the air is drawn into the lungs, this causes for the thoracic cavity volume to increases, during inspiration the diaphragm also contracts, therefore moving the diaphragm downwards. There are three more muscles that contract during the process of inspiration these muscles include the pectoralis minor which contracts when breathing in air. The sternocleidomastoid, which is the muscle in the neck contract. The last muscle that contracts is the scalenes which is also located around the neck. During expiration
