JOINTS
• Joints are places where two or more bones meet.
• There are three main types of joints present in our body.
Fixed/Immovable joints:
• Fixed joints do not allow any movement.
• The joints between the bones of our skull are examples of fixed joints.
Freely movable joints:
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HOW BONES MOVE
• Bones move with the help of joints.
• Joints cannot bring about movement without the help of muscles.
• Muscles bring about movement by contracting (shortening) and relaxing (lengthening).
• One end of a muscle is attached to a movable bone, whereas the other end is attached to a fixed bone.
• When the muscle contracts, it pulls the movable bone.
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X-RAYS
• Sometimes when we are hurt, doctors take an 'X-ray' photograph of the injured part to find out if there is any fracture in the bones.
• X-rays were discovered by German physicist Wilhelm Conrad Roentgen in 1895.
X-ray of hand X-ray of chest
• Roentgen discovered these rays accidentally, while working in his laboratory.
• In various experiments, he found that these rays were able to pass through tissues, but not bones.
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