Introduction
When it comes to human anatomy, some questions can be more popular than others, and one of those most frequently asked is how many ribs does the human have? While it may seem like an easy question to answer, the truth is that the topic is more complicated than it may seem. This article explores the evolution and anatomy of human ribs, their role in breathing, common misconceptions, and even the controversy surrounding the idea of a 13th pair of ribs.
History and Evolution of Human Ribs
Humans are not the only creatures to have ribs and their number has evolved over time. Most reptiles have around 23 ribs, while different groups of mammals have different rib counts. Most non-human primates, for example, have 13 pairs of ribs. However, humans have only 12 pairs.
According to evolutionary biology, humans once had 13 pairs of ribs like most primates before diverging from the other chimpanzees around 5-7 million years ago. The loss of a pair of ribs is likely due to changes in our body structure and upright posture. The gradual development of our current ribcage also helped to narrow down our waist which helped us balance better thus, facilitate to be bipedal.
However, it is also possible for some individuals to have extra or fewer ribs, which is a relatively common condition. These extra ribs, known as cervical ribs, grow at the base of the neck, and while they may not cause any problems, they can also lead to medical complications if they put pressure on nearby arteries or nerves.
Anatomy of the Human Ribcage
The human ribcage is a bony structure that comprises 12 pairs of ribs, the sternum, and the spine. The ribs are attached to the spine and curve around to meet at the sternum, forming a protective cage around our vital organs such as the heart and lungs.
The ribcage can be divided into three portions: the true ribs, the false ribs, and the floating ribs. The true ribs are the first seven pairs that are connected to the sternum by a strip of cartilage, commonly known as the costal cartilage.
The false ribs are the next three pairs of ribs that are connected to the sternum by a shared costal cartilage of the seventh rib, which is why they are also known as the vertebrochondral ribs. The floating ribs are the last two pairs of rib, also called vertebral ribs, that are not connected to the sternum at all.
Each rib has a slightly different shape and function. The upper seven pairs of ribs are commonly called the true ribs. Their function is to protect the heart and lungs while allowing the chest to expand during respiration. The next three pairs are the false ribs that offer lower support to the chest and help to maintain its structure. The last two pairs of ribs, the floating ribs, are not attached to the sternum. They are smaller and lighter, serving minimal functions other than providing some protection to kidney/liver.
The Role of Ribs in Breathing
The human ribcage plays a crucial role when it comes to breathing by act as the primary moving part of your chest, allowing the expansion and contraction of your lungs. The ribs are designed to move around like a bucket handle, allowing the chest to expand and contract. The diaphragm, the breathing muscle located below the lungs and torso, contracts and moves downwards while inhaling, pushing the organs down and increases the volume inside the ribcage. As the ribcage expands, it facilitates lungs to fill up with air. The relaxing of the diaphragm and other breathing muscles ease off the constriction, help to return ribcage and lungs back to its original state and push the air out of your body.
Common Misconceptions About Human Ribs
Despite the extensive information available on the topic of human ribs, there are still many popular myths surrounding them. Some of these common believes include:
Men have one fewer rib than women: Probably one of the most popular myths about ribs. The source of this myth can be traced back to the biblical story of Adam and Eve, where Eve was created using one of Adam’s ribs. In reality, both men and women have the same number of ribs.
Ribs always heal on their own: It is a common belief, but unfortunately, it is not always true. Depending on the situation and seriousness of the injury, some broken ribs may require surgery or extensive time to heal, while others may need nothing more than time and rest.
The Significance of the 13th Rib
One of the most controversial ideas about human ribs is the existence of a 13th pair of ribs. As mentioned above, humans generally have 12 pairs of ribs, but some people believe that there is an exception. This is an old myth with its roots in ancient history, although some people still believe it today. There have been accounts of people being born with a 13th pair of ribs, which has led to the creation of stories, legends, and myths around the subject matter.
In a literal sense, the 13th rib does not actually exist in humans. In some cases where there may appear to be one more rib, it can most often be attributed to either a miscalculation, counting the cartilage between the ribs as a rib itself, or a medical disorder known as Supenemariny which is a rare, genetic disorder where a person is born with too many pairs of ribs, causing them to have 13 pairs of ribs as opposed to the normal 12.
Conclusion
Understanding the anatomy and evolution of human ribs are important to learn so that we can recognize the value and function of the component throughout human history. Aside from protecting our vital organs and providing structure to our chest, human ribs play an essential role in respiration and the movement of air in and out of our lungs. However, despite the extensive information available on the subject, misconceptions, and myths still persist. Therefore, it is essential to separate fact from fiction and learn the truth about human ribs.