Mechanism of Breathing · NCERT Biology

During forceful expiration, which of the following muscles contract?

  1. External intercostal muscles only
  2. Internal intercostals and abdominal muscles
  3. Diaphragm contracting downward
  4. Scalene and sternocleidomastoid muscles
Show answer and explanation

Correct answer: Internal intercostals and abdominal muscles

Forceful expiration is an active process that involves the contraction of internal intercostal muscles (which pull the ribs down) and abdominal muscles (which push the diaphragm up), further reducing thoracic volume.

Difficulty: Medium Question 10 of 20

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