Which muscles are responsible for changing lung volumes and creating pressure differences relative to the atmosphere?

The muscles responsible for changing lung volumes and creating pressure differences relative to the atmosphere are indeed the breathing muscles. These muscles include the diaphragm and the intercostal muscles, among others. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity and thereby decreasing the pressure inside the lungs relative to atmospheric pressure. This allows air to flow into the lungs. Similarly, the intercostal muscles expand the thoracic cavity by moving the ribcage.

During exhalation, these muscles relax, causing the lung volume to decrease and increasing pressure, which pushes air out of the lungs. Thus, the breathing muscles play a crucial role in ventilation, directly influencing lung volumes and the pressure changes that facilitate inhalation and exhalation.