The breastbone, commonly known as the sternum, is a prominent flat bone situated at the center of the chest. It plays a significant role in the human body’s skeletal structure, providing a central anchor point in the upper torso.
Locating the Breastbone
You can easily locate your breastbone by feeling the flat, hard structure in the middle of your chest, running down from just below your throat. This bone is positioned between your collarbones at the top and extends downwards towards the upper abdomen. The breastbone has a general dagger-like or sword-like shape, appearing flat and elongated.
The sternum is composed of three distinct parts that fuse together as a person matures. The uppermost section is called the manubrium, which is the broader, more quadrangular part. You can feel the manubrium just below the notch at the base of your neck.
Below the manubrium lies the body of the sternum, also known as the gladiolus. This is the longest and narrowest section, extending downwards from the manubrium. The body forms the central bulk of the breastbone, connecting to most of the ribs along its sides.
At the very bottom, terminating the breastbone, is the xiphoid process. This small, pointed projection is typically cartilaginous in younger individuals and gradually ossifies, or turns into bone, with age. The xiphoid process can vary in shape and size among individuals.
The ribs attach directly or indirectly to the breastbone, forming the protective cage around the chest cavity. The first seven pairs of ribs, known as true ribs, connect directly to the sternum via their own costal cartilages. Other ribs connect indirectly or not at all.
The Breastbone’s Role
The breastbone performs several important functions, primarily serving as a protective shield for internal organs. Its central location at the front of the chest positions it directly over the heart and lungs. By forming the anterior wall of the thoracic cage, the sternum helps to safeguard these delicate organs from external impact.
Beyond protection, the breastbone acts as an important anchor point for the ribs. It provides structural integrity to the entire rib cage, ensuring that the thoracic cavity maintains its shape and stability. This stable framework is important for the proper expansion and contraction of the lungs during respiration.
The sternum also serves as an attachment site for various muscles. Muscles involved in breathing, such as the pectoralis major and some abdominal muscles, originate or insert on the breastbone. These muscular attachments facilitate movements of the upper body and contribute to the mechanics of breathing.