Anatomy & Physiology: Bones—Sternum.
Structure.
- The sternum is comprised of 3 parts (descending order): manubrium, body, xiphoid process.
- Manubrium: most superior of the 3 parts; flat; name means “handle-like” or the vernacular “breastbone”; the suprasternal notch is distinguishable upon inspection and easily palpateable. The manubrium articulates with the medial ends of the clavicles on either side at the clavicular notch.
- Body: largest piece of the sternum; flattish and elongated. Articulates with the manubrium at the sternal angle. Articulates with the costal cartilages of ribs 2-10.
- Xiphoid process: the most inferior and smallest portion of the sternum. It is triangle-shaped. It’s made of hyaline and doesn’t ossify until about 40 yrs old. The xiphoid is an attachment site for some abdominal muscles. The xiphoid is palpateable and it has a “give”; it can also be painful to even slightly depress that area.
Function.
Clinical Significance.
- Sternal angle: clinical landmark for locating rib #2 and counting ribs as reference points to internal organs like the heart.
- Xiphoid process: incorrect alignment for CPR may cause the xiphoid to fracture off and drive it into (and damage) the internal organs.
Sternum. Used with permission by 3D4Medical.
References
Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.
Cedars-Sinai. (2018). Vertebrae of the spine. Retrieved from https://www.cedars-sinai.org/health-library/diseases-and-conditions/v/vertebrae-of-the-spine.html
Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.
Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.
