Page 27 - Future Stars Science Explorer-5

Now, Move your knee in different directions. Then move your neck in as
many ways as you can. Is there a difference? The neck can be moved in many
directions whereas the knee cannot. This is because the movable joints in the

neck and knee are of different types.

Movable joints are of four kinds.

Ball and Socket Joints : They allow movements
of body in many directions. In this kind of Ilium

joints, one of the bones has a rounded head Acetabulum Femoral
which is the ball. The other bone has a cup-like head

cavity known as the socket. The shoulder joint Joint cavity

and hip joints are examples of ball and socket Joint capsule Femur
joints. Ball and socket joints

Hinge Joint : It allows only back and forth movements.
Such joints are present in the knees, elbow, fingers and

toes. A hinge joint functions like the hinges of a door. It
enables movements similar to the opening and closing

of a hinged door.

Hinge joints

Pivot Joint : It allows the head to turn from
side to side. It is found between the first and
second cervical vertebrae, directly benrathe

the skull. There is a rod-like bone which fits
into a ring, formed by another bone.

Pivot joints

Gliding Joint : It allows bones to slide against each other
in a smooth, gliding motion. This kind of joint is found in

the ankle and wrist. It is also present in the backbone.

Gliding joints
Muscles

Below our skin and above our bones lie soft, fleshy tissues called muscles.

All the muscles of our body together form the muscular system. There are
around 650 muscles in our body. Muscles are made up of bundles of fibres.

27 Science-5