The sternum, commonly referred to as the breastbone, is a flat bone located at the front of the chest. It consists of three main parts: the manubrium, the body (or gladiolus), and the xiphoid process. In total, the sternum is considered as one single bone despite its anatomical divisions. Therefore, the answer to the question is that there is one sternum, but anatomically it is broken down into three distinct sections.
It’s important to note that while the sternum itself is just one bone, it plays a crucial role in the overall structure of the ribcage, serving as an attachment point for ribs and muscles involved in breathing. Understanding its composition can help in grasping how it contributes to the protection of vital organs in the thoracic cavity.