Back Pain Information for Kids

Spinal and Skeletal Bone: Questions and Answers

How many bones are in the human body?
An average adult has 206 bones. Some people have an extra rib or two and may have more bones in their hands and feet.

How many bones are in the spine?
There are 33. The bones in the spine are called vertebrae (ver-tea-bray). Beginning at the neck, there are 7 vertebrae in cervical (sir-vick-all) spine - 12 thoracic (thor-ah-sick) - 5 or 6 lumbar (lum-bar) - 5 sacrum (say-crumb) - 3 coccyx (cock-six). The coccyx is the tailbone.

thoracic vertebra

Thoracic Vertebra

How much do all the bones in the body weigh?
Total bone weight depends on how much the person's entire body weighs. Bones make up about 15% of a person's total body weight. For example, the bones of a person weighing 100 pounds would weigh about 15 pounds.

Are bones alive?
Yes! In fact bones contain thousands of living cells that are replaced as they die. Like other organs in the body, blood brings food and oxygen to bones. The blood also removes waste - you might say that blood takes out the garbage!

What is bone?
Bone is dense and hard yet, slightly elastic. It is made up of different layers of bone tissue, cartilage, blood vessels, and other tissue. The outer layer is compact bone. It is very hard and strong. The inside layer is called spongy bone and it does look something like a kitchen sponge! In the center of the bone is marrow. Within the bone marrow the body makes red blood cells.

What is bone marrow?
In the center of bone is a jelly like matter called bone marrow. Bone marrow is the heart of the body's blood factory. Not only does bone marrow make red blood cells, but it also makes different types of white blood cells. How do bones get blood? The outer layer of bone cells form rings around spaces called Haversian (have-er-shan) canals. The canals are connected to each other. Each canal is tiny and long. A blood vessel runs through each little canal.

Do bones have skin?
Bones have an outer layer that is like a thin skin or membrane (mem-brain). This membrane is called the periosteum (per-eye-os-tee-um). The periosteum can be thick and is filled with blood vessels that help feed the bone. Many nerves also fill the periosteum.

How does smoking affect the body?
Cigarettes, cigars, pipe tobacco and other tobacco products contain hundreds of poisons. Nicotine is a very poisonous substance in tobacco smoke. Carbon monoxide is a poisonous gas found in cigarette smoke. Smoking raises blood pressure, reduces the amount of oxygen in blood, causes mucus to build up in the lungs, and can cause death. People who smoke get sick more often and heal slower than non-smokers.

Updated on: 02/01/10