No matter who you are, you’ve got something that everybody else has got, too: a skeleton! Underneath your skin sits a complex system of bones to keep you upright and moving. Here are some fascinating facts you and your kids can enjoy about the human skeletal system.
How many bones?
It’s common knowledge that there are 206 bones in the human body. But that’s not the case of everyone. Adults have 206 bones; at birth, people have around 270. There are spaces in between a lot of those bones, giving room for everything to grow and, by adulthood, a lot of bones fuse together, reducing the total count.
Why do we need bones?
Can you name the two primary functions of bones? The first is structure. They give bodies their “human” shape. The other purpose: protect organs. The vertebrae of the back bone keeps the spinal cord safe, while the lungs and heart get to do what they do thanks to the protection of the sternum and rib cage.
In Who Knew? Human Anatomy, you’ll learn gobs of fascinating facts about the most sophisticated machine in the world—the human body.
How much weight?
Around 14 percent of your total weight is bone weight.
Hands and feet
The most complicated skeletal structures are the hands and feet. One hand contains 27 bones, while a foot consists of 26. That means over half of an adult’s bones are hand and foot bones.
They aren’t all the same
There are two kinds of bones, and the differences are subtle. Cortical bones are the main, structure-providing bones, and are the denser and harder of the two types. The other are the slightly softer trabecular bones. Some examples of this type: the pelvis, ribs, and skull. They’re not as thick as cortical bones, but they’re still quite hard.
What’s inside of bones? Bone marrow. What’s inside of bone marrow? Stem cells, which go on to become brain, heart, blood, and, of course, bone cells.
Bones are made up primarily of calcium, phosphorus, and sodium, although they’re about 50 percent water.
As strong as granite and concrete
Bones do break, but that’s a relative rarity because they’re so strong. On average, a human bone can withstand as much force as three times the body’s weight. The longest bone in the body is also the strongest bone, and that’s the femur, found in the upper leg. It’s about as strong as both granite and concrete.