Contraction of the external intercostal muscles causes which of the following to occur? a. The diaphragm moves downward. b. The rib cage is compressed. c. The thoracic cavity volume decreases. d. The ribs and sternum move upward. | Numerade

Thermal Contraction & Expansion | Overview & Examples

BREATHING [ANATOMY, PHYSIOLOGY & BIOMECHANICS] Breathing occurs when the contraction or relaxation of muscles around the lungs changes the total volume of air within the air passages (bronchi, bronchioles) inside the lungs. When the volume of the lungs changes, the pressure of the air in the lungs changes in accordance with Boyle's Law. If the pressure is greater in the lungs than outside the lungs, then air rushes out. If the opposite occurs, then air rushes in. Here is a summary of the process