Question

During expiration the diaphragm becomes:

• A. Dome-shaped
• B. Flattened
• C. Normal
• D. Oblique

Answer 1

The correct option is A

Dome-shaped

During expiration, the diaphragm becomes dome-shaped. 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 diaphragm relaxes during exhalation, it causes the muscles to rise superiorly and put pressure on the lungs to remove the air. The diaphragm thus comes back to its normal shape, which is dome-shaped. Whereas during inspiration the diaphragm contracts and becomes flat.