Which part of the respiratory system increases to allow for inspiration?

The rib cage plays a crucial role in the process of inspiration. During inhalation, the diaphragm contracts and moves downwards, which increases the volume of the thoracic cavity. At the same time, the muscles between the ribs, known as the external intercostal muscles, contract to elevate the rib cage. This elevation further expands the thoracic cavity, reducing the pressure within it and allowing air to flow into the lungs.

While the diaphragm is also a significant part of the respiratory system that aids inspiration, the rib cage's elevation is a distinct movement that directly contributes to the increase in the thoracic volume necessary for inhalation. Understanding the mechanics of the rib cage during respiration is essential for grasping how air enters the lungs.