ARRT Patient Care Practice Exam

The act of inspiration will cause elevation of the:

1. Sternum

2. Ribs

3. Diaphragm

4. All of the above

The correct answer is: All of the above

Inspiration, or inhalation, is the process by which air is drawn into the lungs. During this act, several anatomical structures work together to facilitate the expansion of the thoracic cavity, allowing the lungs to fill with air. The diaphragm, a large dome-shaped muscle situated at the base of the thoracic cavity, plays a pivotal role in this process. Upon contraction during inspiration, the diaphragm moves downward, increasing the vertical dimension of the thoracic cavity. Simultaneously, the ribs also elevate during inhalation. This occurs through the action of intercostal muscles, which lift the ribs upward and outward, further increasing the volume of the thoracic cavity. This rib movement creates additional space for the lungs to expand. The sternum, which is connected to the front of the ribs, also rises slightly during inspiration due to the same mechanics—often referred to as "pump handle" motion. This elevation enhances the overall capacity of the thoracic cavity and aids in lung expansion. Together, the coordinated movements of the diaphragm, ribs, and sternum collectively enhance the volume of the thoracic cavity during the act of inspiration, making the answer that all these structures are elevated during this process accurate.