Question

When the external intercostal muscles are relaxed, the lungs are at

• A. Residual volume
• B. Expiration phase
• C. Total lung capacity
• D. None of the above

Answer 1

The correct option is B Expiration phase

The external intercostal muscles are a type of muscle found between the ribs in the human chest area. They primarily aid in inhalation during breathing by moving the ribs upward and creating space in the lungs. During normal quiet expiration, both the external intercostal muscles and the diaphragm relax, allowing the thoracic cavity to contract under its natural elastic recoil.

So, the correct answer is 'Expiration phase'