How does the muscles attached to the ribs make the chest cavity enlarge when we inhale?

When we inhale, the diaphragm contracts and moves downward while the external intercostal muscles between the ribs contract, pulling the ribcage upward and outward. This coordinated action increases the volume of the chest cavity, creating a negative pressure that allows air to flow into the lungs. As the chest cavity enlarges, the lungs expand, facilitating the intake of oxygen. This process is essential for effective respiration.