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7.4A: Thoracic Cage: Sternum

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    7488
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    The sternum or breastbone is a long, flat, bony plate connected to the rib bones via cartilage that forms the anterior section of the rib cage.

     

    LEARNING OBJECTIVES

     

    Describe the structure and function of the sternum

     

    KEY TAKEAWAYS

    Key Points

     

    • The sternum, or breastbone, is a long, flat, bony plate that forms the most anterior section of the rib cage.
    • The primary function of the sternum is the protection of the heart, lungs, and blood vessels from physical damage.
    • The sternum is made of the manubrium, the gladiolus, and the xiphoid process.

     

    Key Terms

     

    • xiphoid process: The most inferior region of the thorax.
    • gladiolus: The body of the thorax.
    • manubrium: The most superior region of the thorax.

    The sternum, or breastbone, is a long, flat, bony plate that forms the most anterior section of the ribcage. The sternum is highly vascular in nature and covered with a thin layer of compact bone providing a degree of flexibility.

     

    Function of the Sternum

     

    This is a drawing of the sternum with its three regions labeled. From top to bottom, they are the manubrium, the gladiolus, and the xiphoid process regions.

    Sternum: This image shows the parts of the sternum.

    Together with the anterior ribs, the sternum helps to protect the heart and lungs from damage, as well as facilitates the expansion and contraction of the thoracic cavity during respiration. During development the sternum is comprised of four individual sections called sternebrae, which fuse to form the sternum in adulthood.

     

    Structure of the Sternum

     

    The sternum is divided into three regions:

    1. The manubrium.
    2. The gladiolus.
    3. The xiphoid process.

    The manubrium is the most superior region of the sternum and articulates with the clavicles or collarbones and the first pair of ribs. The manubrium is the thickest portion of the sternum as it carries the greatest physical load.

    Located below the manubrium, the gladiolus is the longest portion of the sternum and articulates with the ribs, either directly or indirectly, through the costal cartilage

    The thin, pointed xiphoid process forms the most inferior region of the sternum to which the costal cartilage and cartilage of the celiac, or solar, plexus attaches.