Which part of the sternum is commonly referred to as the breastbone?

The term "breastbone" is commonly used to refer to the sternum as a whole, which is a flat bone located in the center of the chest. The sternum is composed of three main parts: the manubrium, the body, and the xiphoid process. Each part plays a role in forming the complete structure known as the sternum.

The manubrium is the uppermost segment of the sternum and connects to the first pair of ribs, as well as the clavicles. The body, which is the longest part, connects to the manubrium above and the xiphoid process below. The xiphoid process is the small, cartilaginous tip at the lower end of the sternum that often ossifies with age.

Since the term "breastbone" can refer to the entire sternum that includes each of these components, stating that all parts are included in that definition is correct. Thus, recognizing that the manubrium, body, and xiphoid process collectively make up what is referred to as the breastbone provides a comprehensive understanding of its structure.