Question

The rib cages move downward and inward in the .......... process.

• A. Inhalation
• B. Inspiration
• C. Expiration
• D. All of the above

Answer 1

The correct option is C Expiration

Expiration is the process of expelling out foul air from lungs. It is a passive process. Expiration is initiated by the relaxation of external intercostal muscles while internal intercostal muscles contract. The diaphragm moves up towards the thorax to its original position. The rib cage is moved downward and inward resulting in reduced volume of the thoracic cavity. Consequently, the intra- pulmonary pressure goes above the atmospheric pressure and the air rushes out. This is how expiration takes place. Hence the correct answer is option C.