Dem Bones

You probably think of death when you think about skeletons. Or maybe you think that skeletons are like scaffolding, holding everything in the body in place, and the bones are like metal bars. True but bones are also very much alive. They aren't just some solid material like metal, they are alive with cells. Human bones have three layers. The smooth, hard outer layer is cortical bone. Beneath this layer are many layers of cancellous bone. Cancellous bone looks kinda like a sponge. Although not quite as hard as cortical bone, it's still pretty strong. The third and innermost layer is the bone marrow. Bone marrow is like a thick jelly, and its job is to produce blood cells. So, as you can see, bones aren't only alive, they're responsible for keeping you alive as much as the heart or the brain!

What Do Bones Do?
Bones make blood cells.
Bones are the framework for your body.

How Many Bones?
Humans are born with 300 bones, but adults only have 206 bones. So what gives? Some of the 300 original bones in a baby are made of regular bone and some are made of a material called cartilage. Cartilage is soft and flexible to start, but over the years the cartilage grows and slowly hardens into bone. Also, some bones fuse together. All of this is part of the normal growth process.

Some time between the ages of 17 and 21, this growth process ends and your bones are as big as they're going to get. And like magic, you end up with 94 fewer bones than you started with.

Bits of Bones
More than half of the body's 206 bones are in the hands and feet.
The skull is composed of 30 different bones.
The smallest bone in the body is the stirrup bone inside the eardrum. It is less an inch long.
The largest bone in the body is the femur which is the leg bone that runs from the hip to the top of the kneecap (patella.)
Everyone's heard of the funny bone, but did you know that humerus is the real name of the long bone that runs from your elbow to your shoulder.

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