To have a cracking sternum is a fairly irregular condition that can alert more than one. Cracking can occur intentionally or provoked. But whether it's one or the other, the only question is: is that bad ? Answers and explanations in this article.
Definition and anatomy
The breastbone is the odd bone located on the middle and anterior part of the thorax. It is a flat bone whose structure is entirely palpable under the skin. The first seven pairs of ribs, called sternal ribs, are directly connected to the Sternum via their costal cartilage.
With all the ribs and vertebrae behind, the sternum forms the rib cage. The latter is responsible for containing and protecting the mediastinal elements such as the heart, the great vessels and the lungs. On the other hand, the sternum also serves as an anchor point for most of the muscles responsible for breathing, head and arm movement.
Structurally, the sternum is formed by the fusion of three bone segments:
- The sternal manubrium: It articulates on either side with the two clavicles and the first pairs of ribs.
- The sternal body: The longest part of the sternum, it articulates with the last five pairs of sternal ribs.
- The xiphoid process
These three sternal segments are interconnected by two immobile cartilaginous joints called synchondroses. Thus, we distinguish:
- The manubrio-corporeal synchondrosis connecting the base of the manubrium to the upper part of the sternal body. It is at this level that the second pair of sternal ribs are articulated.
- Corporo-xiphoid synchondrosis attaching the base of the sternal body to the xiphoid process.
Disorders in the sternum
Due to its anatomical location, the sternum is often the site of various disorders. Among the most common are:
Bone and joint disorders
- The fracture of the sternum : On the one hand, it may be caused by direct trauma following a road or sports accident. On the other hand, it is caused by osteoporosis which leads to great fragility of the bone structure.
- Sternoclavicular dislocation : This is the dislocation of the joint formed by the manubrium and the clavicle.
- Le Tietze syndrome : It corresponds to an inflammation of the cartilage joining the ribs and the sternum. This syndrome is manifested by a sharp pain localized at the level of the affected cartilage.
Chest pain
The sternum is a real anatomical crossroads, it is connected with many structures in the thorax. When one of these structures is affected, the pain can reverberate to the level of the sternum. The main causes of sternal disorder of thoracic origin are:
- Cardiac pathologies such as angina pectoris, myocardial infarction and pericarditis.
- Vascular pathologies such as pulmonary embolism.
- Pulmonary pathologies such as pneumothorax, pneumonia, pleurisy or a simple respiratory infection. In lung damage, the chest pain is aggravated with each effort of coughing.
Digestive disorders
Sternal disorders can also be caused by digestive disorders such as esophagitis, hepatic colic attacks, gastritis or ulcers.
Rare lesions of the sternum
There are mainly two rare disorders of the sternum that can be the cause of sternal disorder :
- The sternal cleft: During embryonic life, the sternum did not completely close. It is a sternal malformation of unknown origin until now.
- Sterno-costo-clavicular hyperostosis: This disease is manifested by the increase in volume of the sternum, the clavicles and the first ribs.
breast cancer
Although rare, cancer of the sternum also causes serious sternum disorders. It is said to be primary when the sternum itself is cancerous. It is said to be secondary when the structures surrounding the sternum are cancerous, but the cancer has spread to the level of the sternum.
muscle disorders
As mentioned earlier, the sternum is the point of attachment for many muscles. Damage or dysfunction of these muscles can cause pain in the sternum.
Cracking bones, where does it come from?
When you move, you may hear the bones cracking. These crackles can occur involuntarily, but they can also be provoked. They occur more specifically in movable joints.
A mobile joint is formed by an articular cavity delimited by two bony extremities. This cavity is filled with a viscous liquid called “synovial fluid”. The whole is then wrapped in a resistant fibrous membrane called “synovial membrane”
The main role of synovial fluid is to lubricate the articular cartilaginous surfaces. In this way, the joint can perform movements without causing pain or friction. It can happen that a depression forms within the joint cavity when performing certain movements.
Thus, the pressure in the synovial fluid suddenly decreases and the dissolved gases present in this fluid come together and form a bubble. This is a purely physical phenomenon called "cavitation". The cracking of bones occurs when the latter bursts into numerous micro-bubbles.
Sternum cracking, should you be worried?
The joint that the sternum forms with the first pair of ribs is a synarthrosis, it is immobile. The manubrio-corporeal and corporo-xiphoid synchondroses cannot be mobilized either.
The crackles that we hear coming from the sternum thus come from the joints connecting the sternum with the other six sternal ribs. Even if the movements of these joints are more limited, they are indeed movable joints. The mobility of these joints allows the ribs to rise when you take a deep breath. The synovial fluid contained in these sterno-costal joints can undergo the phenomenon of cavitation.
In other words, the cracking of the sternum does not necessarily mean serious harm. When it's not associated with increased pain, there's no need to worry. Cracking in the sternum are purely physiological phenomena that occur as a result of a stretch, a false movement or a simple sudden movement. A cracking sternum is the same as cracking fingers.
However, if the crunches cause pain, it may be a sign a sternum disorder. If in doubt, it is best to consult a healthcare professional right away.
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