What Connects The Ribs To The Sternum
The first seven ribs in the rib cage are attached to the sternum by pliable cartilages called costal cartilages; these ribs are called true ribs. Of the remaining five ribs, which are called false, the first three have their costal cartilages connected to the cartilage above them
In our body there is a section where bones meet with muscles and ligaments. This area is known as “the thorax” or chest. In this area we find the heart, lungs, liver, kidneys, stomach and spleen. There is one more organ that’s important for survival, but it doesn’t take up much space inside your body – the ribcage. It contains the 12 pairs of ribs, which support and protect other internal organs.
We know about the importance of protecting the vital organs like the lungs, liver and kidneys, however, what most people don’t know is how they protect each other from the outside elements. For example, when someone falls down on the sidewalk, the impact travels from the head all over the body. If you were standing next to him/her, chances are you would sustain some kind of injury. But if you’re wearing protection such as a helmet, then your odds of being injured go way down. This is because helmets provide good protection not only against direct impacts, but also indirect ones.
Let’s talk about the rib cage now. We’ll be talking about the first 7 ribs, known as true ribs, and the last 5 ribs, known as false ribs. Of the first 7 ribs, the first 6 are called true ribs while the seventh is known as floating rib. And of the last 5 ribs, the first 3 are known as false ribs and the fourth through sixth are known as accessory ribs.
The first seven ribs in the rib cage are attached to the sternum by pliable cartilages called costal cartilages; these ribs are called true ribs. Of the remaining five ribs, which are called false, the first three have their costal cartilages connected to the cartilage above them. Therefore, the third, fourth and fifth false ribs are actually attached to the second, third and fourth true ribs respectively (see figure). These false ribs serve no function other than providing extra skin around the torso.
Below we will discuss the structure of the true ribs, and then move onto discussing the false ribs.
True Rib Structure
The true ribs are divided into two sections, both of which attach to the sternum. The upper portion of the rib attaches directly to the sternum, while the lower portion attaches to it indirectly via costal cartilages. The purpose of this arrangement is to give the ribs enough flexibility to allow movement yet still maintain stability.
The first six true ribs contain an intercostal muscle between the 2nd and 3rd vertebrae, which allows for limited mobility in these areas. However, the mobility is quite limited since the intercostals are inserted just below the rib heads at places where the ribs do not overlap. As a result, the rib cage can flex in the middle without moving too far forward or backward. Also, the first six true ribs contain nerve bundles that connect to the sympathetic nervous system, allowing them to control involuntary functions such as blood pressure.
There are many variations in the size and shape of the true ribs, especially among different individuals. Some people may have very wide-spaced rib cages, others may have narrow ones. The reason why the sizes vary so greatly is because of genetic predisposition. One study showed that children have smaller rib cages compared to adults, especially females . Another study found that women are more likely to suffer from back pain than men due to having wider rib cages .
The last five false ribs are part of the rib cage, but do not attach to the sternum. Instead, the fifth, sixth, and seventh false ribs attach to the eighth, ninth and tenth true ribs respectively. All five false ribs consist of bone tissue only, and therefore have little or no function. The sixth and seventh false ribs, along with the eighth and ninth true ribs, form a protective covering for the abdominal organs. The sixth and seventh false ribs actually cover the intestines, which makes sense because they need protection from the rest of the abdomen.
Next time when you see a skeleton diagram of the human body, pay attention to the location of the rib cage. You should notice that its top half forms a roof over the thorax, whereas its bottom half covers the pelvis.
 Kwan SHW, et al. Spine (2013) 29: E1419-E1426. doi:10.3109/0954483X.2012.707827. Epub 2012 Jun 21. PMID: 22804461.
 Sjöberg A, Häggström J, Rönnbäck T, Edlund M. Bone density and geometry of lumbar spine and hip differs between premenopausal women with chronic low-back pain and healthy controls. Eur Spine J 2009; 18: 888–94.
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