- Mechanism of breathing movements (picture on the left)
- The change in shape of the thorax during inspiration and expiration(picture on the right)
Under the influence of nerve impulses muscles involved in breathing contract (diaphragm, intercostal muscles, and others.). The diaphragm lowers (flattens), thereby increasing the vertical volume of the thoracic cavity. Other auxiliary respiratory muscles increase the thorax breadth. As a result, the lungs stretch, the pressure therein drops and becomes lower than the atmospheric pressure. Due to the pressure difference between the atmospheric and pulmonary air, the outside air rushes into the lungs. As you exhale the same muscles relax (diaphragm thus rises), the ribs are lowered, the volume of the thorax decreases, the lungs are compressed, the pressure in them increases (above atmospheric pressure) and the air rushes out. Muscles involved in breathing, divided into:
- inspiratory muscles (breathing proper and auxiliary ones)
- expiratory muscles.
Breathing proper muscles change the volume of the thorax.
Auxiliary breathing muscles perform two functions, the main - the movement of the peripheral links of the body (head, shoulder blades, pelvis). However, when the peripheral links are fixed, these muscles can move the ribs.