How Many People Have Extra Bones in Their Skeleton?

It's well known that infants possess a greater number of bones compared to adults: Newborns may have between 275 and 300 bones, with sma...

It's well known that infants possess a greater number of bones compared to adults: Newborns may have between 275 and 300 bones, with smaller bones merging and becoming more rigid as the child matures.most adults possess just 206. (Having tinier, softer bonesprovides infants with the additional flexibility required to curl up in the uterus and navigate through the birth canal.

But can adults develop additional bones?

Some grown-ups actually possess more than 206 bones. These additional ones, referred to as accessory bones orsupernumerary bones, can happen when bones fail to join properly during growth, according to a 2024 study published in the journalScientific Reports.

Nevertheless, there are usually no clear indicators that a person has more bones than the average.

It's quite simple to be unaware that someone possesses an additional bone,Dr. Vandan Patel, an orthopedic surgeon at the Institute for Foot and Ankle Reconstruction at Mercy Medical Center in Baltimore, told Live Science. Typically, additional bones do not lead to any issues. "Frequently, individuals discover they have an extra bone when an X-ray is taken for a different reason and it is discovered by chance," he mentioned.

Even if additional bones are visible on X-rays, they are often missed or mistaken for broken pieces or changes due to aging, saidEren Ogut, an associate professor of anatomy at Istanbul Medeniyet University. Overall, "studies indicate that they are found in approximately 10 to 30% of the general population," but "their actual frequency is probably greater than what is typically recognized," Ogut said to Live Science.

Accessory bones are frequently found in the foot and ankle, according to Patel. The most prevalent accessory bone is referred to as the os trigonum, he mentioned. "This occurs in approximately 10 to 25% of individuals," Patel explained. "It is situated at the back of the ankle joint. It may lead to discomfort, particularly when pointing the toes and flexing the ankle downward, like in a ballet dancer performing en pointe."

Another frequently encountered accessory bone is referred to as the os tibiale externum, or alternatively, the accessory navicular. "It occurs in as many as 12% of individuals," Patel explained. "It is situated on the inner side of the foot, adjacent to the regular navicular bone. At times, the navicular bone may seem larger than usual. This condition can lead to discomfort in the arch and is commonly associated with flat-footedness."

Physicians are also aware of several rare additional bones, typically through research on cadavers or medical imaging, according to Ogut. An example is the os acetabuli, an extra bone in the hip that might be linked to hip discomfort, he mentioned. This additional bone appears in less than 5% of people, Ogut stated in a 2025 review paper in theBratislava Medical Journal.

Occasionally, individuals may have additional ribs. As many as 1% of people are born with one or even two extra bones in their neck, referred to as cervical ribs, according to theCleveland Clinic. This uncommon bone is not similar to a regular rib; it may be more upright or slanted rather than horizontal like the ribs in the chest. Usually, cervical ribs do not cause any issues, but they can result in discomfort or weakness in the arm. In these situations, physical therapy or medication may provide relief. A surgeon can also remove them, as they have no functional role, according to the clinic.

Human skeleton quizWhat can you tell me about the bones in your body?

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