Breathing Out (Exhalation) When you breathe out, or exhale, your diaphragm relaxes and moves upward into the chest cavity. The intercostal muscles between the ribs also relax to reduce the space in the chest cavity.
Keeping this in view, what causes the diaphragm to contract?
When you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. This increases the space in your chest cavity, into which your lungs expand. The intercostal muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.
Is the diaphragm flat when relaxed?
When we inhale, the diaphragm contracts and is drawn inferiorly into the abdominal cavity until it is flat. During exhalation, the rib cage drops to its resting position while the diaphragm relaxes and elevates to its dome-shaped position in the thorax.
What happens to the diaphragm during expiration?
This happens due to elastic properties of the lungs, as well as the internal intercostal muscles which lower the rib cage and decrease thoracic volume. As the thoracic diaphragm relaxes during exhalation it causes the tissue it has depressed to rise superiorly and put pressure on the lungs to expel the air.