The human body has 206 bones, including the two ear ossicles and the hyoid bone. This is not to say that the average person has equal ribs or that these bones are the same shape or size. Are you wondering how many ribs are in the human body?
The bottom of every rib has a joint that attaches to a vertebra and can move up, down, and side-to-side.
How Many Ribs Are in the Human Body?
The ribcage comprises individual bones called ribs and cartilage in between them. There are 12 pairs of ribs, 24 in total, and each pair looks like a small boomerang with an upward curve at the top of it.
How Many Ribs Do Humans Have?
The answer is 12 thoracic vertebrae and 24 ribs.
The thoracic vertebrae are the bones that make up the rib cage: 12 on each side of the spine (24 in total). The ribs start at the top of these vertebrae and attach to them at the front of the chest.
Some people think they have an extra rib compared to others, but that’s not true. People with more or fewer than 12 pairs of ribs are just fine as they are.
The only time it’s a problem is when you have too many or not enough ribs for your organs to fit into your body correctly.
If this happens, it can cause organ problems, like shortness of breath, lung disease, and even chronic pain due to organ pressure.
Causes of Rib Number Variations
Many factors can cause rib number variations. In some cases, irregularities in the rib cage may be genetic; a person may be born with a rib that does not attach to the sternum.
Another cause of variation is an injury to the ribs.
Ribs are thin and easily broken, and injuries may result in their separation from their attachments to the sternum. Rib number variation may also occur as parts of a developmental disorder, such as thoracic insufficiency syndrome or Pectus excavatum.
Rib number variations occur when the rib cage changes position due to physical activity. The rib cage does not lie flat on the thoracic vertebrae, which are the bones that make up the back of your spine but instead curve in and out slightly.
This allows for deep breaths and chest expansion. But it also means that during physical activity, the rib cage may shift slightly, resulting in rib number variations.
The most common cause of rib number variations is exercise, particularly running. As you run and your body increases its heart rate and blood pressure, your muscles contract and expand to support a faster pace. This can push your ribs out of place, resulting in a lower or higher number than usual.
The cervical rib is a congenital anomaly. It is a non-hereditary condition and is one of only two types of ribs (the thoracic rib, which also causes rib number variations). It is characterized by one or more extra ribs in the cervical region (the neck) of the human body.
This anomaly can be present in any part of the cervical region. Still, they usually appear at the seventh to ninth vertebrae in the lower neck in those cases with cervical ribs. This means that most cases of cervical ribs affect vertebral levels C7–T1.
The cause of this anomaly is unclear, but it has been suggested that certain factors can cause it during fetal development. These include:
Genetics – Cervical ribs are commonly found in families with a history of congenital abnormalities and may be passed down genetically to offspring.
Sex Hormones – It has been determined that females are twice as likely to develop cervical ribs than males. This can be explained by the fact that females generally have more sex hormones while developing in utero than males.
Trisomy 21 (Down Syndrome)
Down syndrome is a genetic disorder that causes a person to have an extra chromosome in their cells. This extra chromosome leads to Down syndrome’s physical and cognitive characteristics.
It is most commonly caused by Trisomy 21, which occurs when three copies of chromosome 21 instead of two.
Trisomy is one of the leading causes of a missing or abnormal rib number. Rib number variations can range from having either 13 or 14 ribs to having over 20 ribs or even more than 40 ribs!
These variations were discovered during autopsies from ancient Greece, where it was not uncommon for enslaved people to be over-represented in burial populations, indicating an increased incidence of Down syndrome in the population.
Spondylocostal Dysplasia (SDC) is a congenital disorder characterized by vertebrae, ribs, and sternum defects. Causes of rib number variations in patients with SDC can be attributed to a variety of factors, including both genetic and environmental causes.
The most common variation of rib number is Spondylocostal Dysplasia (SDC), which occurs because of a defect in one of the genes that control rib development. Without this gene, the spine and thoracic cage don’t develop correctly and cannot support all 12 rib bones.
This condition can result in breathing problems, spinal deformities, and heart defects.
Spondylocostal dysplasia affects only 1 in every 3 million individuals.
There are multiple causes of variations in rib number. Spondylothoracic dysplasia is the most common cause of variations in rib number, affecting around 75% of people with this syndrome.
In spondylothoracic dysplasia, there is an abnormality in the development of the vertebrae and ribs; the vertebrae are misaligned, and the ribs are underdeveloped or absent.
Spondylothoracic dysplasia can be a genetic disorder where a child inherits it from their parents, but an error can also cause it during fetal development.
Goldenhar Syndrome (Oculo-Auriculo-Vertebral Spectrum)
The most common cause of rib number variations is Goldenhar Syndrome (Oculo-Auriculo-Vertebral Spectrum). This is a genetic disorder that affects 1 in 30,000 newborns.
The syndrome causes underdeveloped bones in the face and chest and underdeveloped spinal vertebrae and ribs. Rib anomalies can cause many problems with the lungs, heart, and other organs.
Kidney problems and hearing loss are symptoms of this ailment. Children born with Goldenhar often have a cleft palate and/or cleft lip. In severe cases, children can be born missing their noses or parts of their mouth.
Now you know how many ribs are in the human body. Unfortunately, some people experience problems or pain with their ribs.
Rib fractures, tumors on the ribs, or infections of the ribs usually cause rib abnormalities. These conditions can cause respiratory problems, pain, and difficulty breathing.
The treatment for these issues is surgery to repair the damage. Surgeons will remove any excess bone or tissue so that the ribcage can expand and contract smoothly.
The surgeon will also insert a chest wall brace to aid in recovery.