When the Diaphragm and External Intercostal Muscles Contract

Question

When the diaphragm and external intercostal muscles contract,
A) the volume of the thorax increases.
B) the volume of the thorax decreases.
C) the volume of the lungs decreases.
D) the lungs shrink.
E) expiration occurs.

Accepted Answer

When the diaphragm and external intercostal muscles contract, the volume of the thorax (chest cavity) increases, leading to a decrease in pressure within the lungs, which then facilitates inhalation of air.