Question

Mark the correct pair of muscles involved in the normal breathing in humans.

• A. External and internal intercostal muscles
• B. Diaphragm and abdominal muscles
• C. Diaphragm and external intercostal muscles
• D. Diaphragm and intercostal muscles

Answer 1

The correct option is D Diaphragm and intercostal muscles

Breathing involves two stages : inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out. Inspiration can occur if the. pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure, i.e., there is a negative pressure in the lungs with respect to atmospheric pressure. Similarly, expiratibn takes place when the intra-pulmonary pressure is higher than the atmospheric pressure. The diaphragm and a specialised set of muscles-external and internal intercostals between the ribs, help in generation of such gradients.

So, the correct answer is 'Diaphragm and intercostal muscles'.