Question

During forced expiration, actively contracting muscles include the

• A. diaphragm
• B. internal intercostals
• C. abdominal muscles
• D. all of these

Answer 1

The correct option is D all of these

Relaxation of the diaphragm and the inter intercostal muscle returns the diaphragm and sternum to their normal position and reduce the thoracic volume and thereby the pulmonary volume.

This leads to an increase in the intrapulmonary pressure to slightly about atmospheric pressure and causes the expulsion of air from the lungs.

The abdominal muscles help in increasing the strength of expiration.

So, the correct option is 'all of these'