Question

Which of the following is not a true statement?

a. When the diaphragm relaxes, it returns to a domelike shape.
b. When the diaphragm contracts, it pulls the floor of the thoracic cavity downward.
c. Changes in thorax size bring about inspiration and expiration.
d. Raising the ribs decreases the depth and width of the thorax.

Answer 1

The correct answer is D, because raising the ribs increases the depth and width of the thorax. During inspiration, the external intercostals raise the lower ribs up and out, increasing the lateral and anteroposterior dimensions of the thorax. This movement helps the lungs to expand.