THE SKELETAL
SYSTEM
Can you touch your backbone, your
ankle bone, and your knee?
These are bones that are all part of your
skeleton.
Just as a house could not stand without
its wooden frame, your body cannot
stand without its skeletal
system.
Your skeleton also protects organs inside
your body, such as your brain, heart,
and lungs.
Your skeletal
system also helps
you move.
Muscles that move
your body are
attached to your
skeleton.
BUILDING STRONG BONES
Your skeletal system needs certain
minerals to help it stay healthy.
Minerals, such as calcium, help
build bone tissue and keep
bones strong.
One bone attaches to
another bone at a joint.
Joints can be classified by
the type of movement
they allow.
Tissues around joints
protect them. The tissues
also help hold the bones
together at the joint.
Ball-and-socket joints
allow the most
movement of any type of
joint. Your shoulder and
your hip have ball-andsocket joints.
The end of one bone
(ball) fits into a bowlshaped area (socket) in
another bone. These
joints allow your bones to
have CIRCULAR
MOVEMENT.
A hinge joint lets your bones move
backward and forward, the way a door
moves. You can bend or straighten your leg
because of the hinge joint at your knee.
THE HUMAN
SKELETON
The adult human skeleton
has 206 bones.
Some of the biggest bones
are labeled in the following
picture:
(cranium)
(pelvis)
Bone with enough
calcium
Bone with lack of
calcium
CALCIUM-RICH FOODS