The New Childrens Encyclopedia

BONES

275

BONES AND JOINTS

Bones are living tissue that contain blood

vessels, nerves, and cells. They are strong,

but light, and if they get broken, they can

heal themselves. You can bend and move

your body because you have lots of joints.

These are where two bones meet and

move over each other.

TAKE A LOOK: X-RAYS

If you have a broken bone, an X-ray

allows your doctor to see what is

happening beneath the skin.

PINNING A BONE A bone can heal

itself if broken, but after an especially bad

break a surgeon may put a metal pin along

the bone to hold it rigid while it mends.

A fracture can take up to eight weeks to heal.

THE FIRST XRAY was taken in 1895

by German physicist Wilhelm Röntgen. He

took an X-ray of his wife’s hand that clearly

showed the shadows of the bones and the

lighter shadowing caused by the soft tissues.

Ribs help you
breathe. They also
protect the heart
and lungs.

Breastbone (sternum)

Upper arm bone

(humerus)

Ulna

TYPES OF JOINT

Some joints (such as your elbows) allow

you to bend in one direction. Others (such

as your shoulders) allow circular movement.

O

Saddle joints are found at the base of

your thumbs.

O

Ball-and-socket joints are found in your

shoulder.

O

Hinge joints are found in your knees.

O

There’s a pivot joint at the top of your

spine.

O

Gliding joints are found in the ankles

and wrists.

Gliding or

plane joint

Hinge

joint

Ball-and-

socket joint

Saddle

joint

Pivot

joint

Spine or backbone

(vertebral column).

This is the body’s

central support.

Shoulder blade

(scapula)

Collar bone

(clavicle)

Radius

There are four main types

of bone: long (such as the

thigh bones), short (such as the

heel bones), flat (shoulder

bones), and irregular (such as

your vertebrae). There are

also small, round bones

with a funny name:

sesamoid (such as

the kneecap).

7

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THE HUMAN BODY