Question

Identify the correct option
Statement – I: The contraction of internal intercostals muscles and lateral abdominal muscles help in forced expiration.
Statement – II: The contraction of phrenic muscles increases the volume of the thoracic cavity in antero-posterior axis.

• A. Statement I and II are correct.
• B. Statement I is wrong and II is correct.
• C. Statement I is correct and II is wrong.
• D. Statement I and II are wrong.

Hint:

Phrenic nerve controls the diaphragm—key muscle for inspiration; forced expiration uses abdominal muscles.

Answer 1

The Correct Option is A

Both statements are scientifically accurate. During forced expiration, the internal intercostals and abdominal muscles contract to push air out. Simultaneously, contraction of the diaphragm (controlled by the phrenic nerve) increases the thoracic cavity’s volume antero-posteriorly during inspiration.