Skeletons & Muscles
Science: Year 3 & 4 National Curriculum, topic 2.2.1
Skeletons and Muscles
Animals that have bones inside their bodies are called 'vertebrates'. The bones in the body of an animal form the animal's 'skeleton'.
Bones for support
- Bones are used to help hold our bodies up.
- Long bones in our legs help us to stand.
- A set of small bones in the spine (backbone), help to hold up our body.
- Think of other places where we have bones that support our body.
Bones for protection
- Our internal organs are soft and could be easily damaged if they didn't have protection.
- Bones are made of a hard material.
- Bones help to protect some organs.
Bones for protection examples
- The skull protects the brain.
- The ribs protect the lungs.
- The sternum (breast bone) protects the heart.
Bones can be broken
- Bones can still be broken if there is a strong enough force.
- When bones break, they can repair themselves.
- Children have bendier bones than adults.
Bones for Movement
The bones of the skeleton give support and protection and help animals to use their muscles to move.
Bones for movement
- Animals use their muscles to move.
- In vertebrates (animals with backbones), muscles are attached to bones.
- Attached means stuck on to.
Pairs of muscles
- Pairs of muscles in our arms and legs help us to move them.
- The muscles contract (shorten) and pull the bone.
- Muscles contracting makes bones move.
- The bone needs to be part of a joint to be able to move.
Movement example
- Sit on a chair and lift your foot off the ground in front of you by straightening your leg at the knee.
- The muscle in your thigh (top part of your leg) is contracting.
- The muscle pulls the shin bone below the knee and makes your leg straighten.
- The knee is a joint.
Joints
- The knee is a joint.
- A joint is where two bones come together but can move.
- The elbow, hip and shoulder are all joints.
- If you put your hand on your thigh muscle when you bend and straighten your leg, you can feel it contracting and relaxing.
Strengthening muscles
- Exercise helps to build up muscle strength.
- A lack of exercise makes our muscles weak.
Test yourself on Skeletons & Muscles
Which of these is true about bones?
What are bones needed for in our bodies?
When you are sat on a chair and you straighten your leg, which muscle contracts?
What is a joint?