cai

1. Objective
Demonstrate how the skeletal system
enables us to move.
Science Concept
The way bones are held together, at the
joint determines the kind of movement.
The Skeletal System Helps Us
Move

2. Motivation
 Move your arms up and down.
 Move them clockwise and then
counterclockwise.
 Move your legs up, down, and around.
1. Why can you move your arms and legs
in different ways?
2. Are there parts of your body you
cannot move in different directions?

3. The Joints
The bones in your body are held
together at different places.
The place where two bones
meet and come together is
called a joint.
The way bones are held
together at the joint determines
the kind of movement you can

4. Ball and Socket
jointPivot joint
Hinge joint Saddle joint
Conyloid jointGliding joint

5. Ball and Socket joint
 Your shoulder bone and arm bone
meet to form a movable joint. Ball
and socket joints allow movement
in different directions.
 Ball-and-socket joints are a
special class of synovial joints that
enjoy the highest freedom of
motion in the body thanks to their
unique structure. The shoulder
and hip joints are the only ball-
and-socket joints in the human
body due to the need for great
motion at the end of the body’s
limbs and the vast amount of
Back to
diagram

6. Pivot Joint
 The joint in your head is a pivot joint. It
allows you to turn your head while the other
bones in your body do not move.
Back to
diagram

7. Hinge Joints
 Let bones move back and forth. Your lower
joints and your elbow joints are examples of
hinge joints.
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diagram

8. Gliding Joints
 The small bones of the wrist slide over each other. The
joint that connects the lower arm to the hand is a gliding
joint.
(Look at the joint that connects the lower leg to the foot. In
what way is it similar to the wrist?)
 Your backbone runs the length from the base of your
skull down to the hips. The backbone is made of
separate bones stacked one on top of the other and
joined by gliding joints.
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diagram

9. Saddle Joint
 A saddle joint is more versatile than
either a hinge joint or a gliding joint. It
allows movement in two directions. The
saddle joint gives the human thumb the
ability to cross over the palm of the
hand.
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diagram

10. Conyloid Joints.
 These joints are similar to ball-and-socket
joints, just without the socket (the "ball"
simply rests against another bone end).
Back to
diagram
EVALUATIO
N

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