In order to expand the volume of the thoracic cavity during inhalation, what must occur?
a. the diaphragm moves upward
b. the ribs compress
c. inspiratory muscles relax
d. inspiratory muscles contract
Answer: D
In order to expand the volume of the thoracic cavity during inhalation, what must occur?
a. the diaphragm moves upward
b. the ribs compress
c. inspiratory muscles relax
d. inspiratory muscles contract