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posted: 8/12/2013 12:33 PM

Skeleton is the scaffolding that supports the human body

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  • Dr. Rebecca Carl, pediatric sports medicine physician at Ann and Robert H. Lurie children's Hospital of Chicago, examines Ethan Valenciana, 12, of Chicago.

    Dr. Rebecca Carl, pediatric sports medicine physician at Ann and Robert H. Lurie children's Hospital of Chicago, examines Ethan Valenciana, 12, of Chicago.
    Courtesy of Mike Tangorra


You wanted to know

"Is it possible to be born without all the bones in your body?" asked students in Nancy Sullivan's sixth-grade class at Frederick Nerge Elementary School, Roselle.

Human beings, homo sapiens to be exact, are defined as having an interior supporting skeleton.

This is what makes people and primates different from, say, jellyfish, which have no bones, or lobsters, which have a type of skeleton on the outside.

The skeleton is what makes homo sapiens unique in the animal world. The skeleton helps humans support their weight and walk upright using two legs. It provides a special mechanism for thumbs to move, allowing the thumb bone to rotate within the socket, helping fingers to pick up and hold objects.

"A skeleton is the scaffolding, or support, for the body," said Dr. Rebecca Carl, assistant professor of pediatrics at Northwestern University and pediatric sports medicine physician at the Ann & Robert H. Lurie Children's Hospital Institute for Sports Medicine.

Technically, babies are born with a large proportion of cartilage, soft bone, as well as bone. The cartilage begins the process of converting to bone in the womb and continues to harden for a long time.

"In fetal development, there's a cartilage skeleton and it begins to harden into bone before birth. It is possible to have some missing individual bones; you're born with more of a skeleton that's a mixture of cartilage and hard bone, which gradually hardens into adult bone," Carl said of the process called endocrinal ossification.

"It's like a seed that expands from a small center, like the top of the femur or thigh bone, and within six months it quickly spreads to cover the whole bone."

Only the top of the thigh bone is cartilage at birth -- the remainder is hard bone, she added.

Bone serves a very important protective function.

"The brain is vulnerable to injury and is soft. The skull, a bony cap covering the brain, cradles the brain and acts as the first line of defense when there's an injury," Carl said.

"The spinal cord is protected by the backbone like a series of Lincoln Logs. Jaws help with eating and the skull protects the ear canals."

But that's not all. Bones also allow for motion -- large action movement like running and jumping and fine motor skills needed to thread a needle or color a picture.

Carl said bone continues to harden as young people grow into their teens and early 20s.

"Most of the growth plates are still producing new bone until age 14 for girls and 16 for boys," she said.

Each year, there are nearly 375,000 emergency room visits for children up to age 14 because of knocks to the head called concussion, according to the Centers of Disease Control.

Carl is conducting research that involves kids, coaches, parents and physicians to better understand these serious brain injuries. She hopes to help find tools that will assist physicians with correct diagnosis of this serious concern.

How can you make sure your bones are healthy?

"Calcium and vitamin D," Carl said. "Everyone has calcium in their blood. The difference is that a body without enough calcium will borrow it from bone, which weakens the bone. You can build a bone bank until you're in your 20s by consuming extra calcium. This will help you all the way into your older years."

Add calcium to your diet by drinking milk or juice with added calcium. Fish oil and vitamins can also provide needed calcium and vitamin D, Carl explained. But don't overdo it. Eat only the amount recommended for your age, found online on the National Institutes of Health fact sheet,

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