What are the functions of the skeleton, and how do joints allow movement in sport?
The functions of the skeletal system, the main bones and types of bone, the types of synovial joint, and the movements they allow at the joints used in sport.
A focused answer to the WJEC GCSE PE topic on the skeletal system, covering the functions of the skeleton, the main bones, the types of synovial joint (ball and socket, hinge), the structure of a synovial joint, and the joint movements used in sporting actions.
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What this dot point is asking
WJEC wants you to state the functions of the skeleton, name the types of synovial joint and their structure, and describe the movements they allow in sporting actions.
Functions of the skeleton
Learn at least four of these, with an example where you can.
- Support: gives the body shape and holds it upright.
- Protection: the cranium protects the brain, the ribs protect the heart and lungs, and the vertebrae protect the spinal cord.
- Movement: bones act as levers that muscles pull on at the joints to create movement.
- Blood cell production: red and white blood cells are made in the bone marrow.
- Mineral storage: stores minerals such as calcium and phosphorus, which keep bones strong.
Bones also provide anchorage (attachment points) for muscles and tendons.
Synovial joints
The two key types at GCSE are:
- Ball and socket joint (shoulder, hip): the rounded head of one bone fits into the cup of another, allowing movement in all directions - flexion, extension, abduction, adduction and rotation.
- Hinge joint (knee, elbow): allows movement in one plane only - flexion and extension, like a door hinge.
The structure of a synovial joint
The parts of a synovial joint each have a job, and the exam often asks for them:
- Cartilage: smooth tissue covering the ends of the bones, reducing friction and absorbing shock.
- Synovial fluid: a lubricating fluid that reduces friction and lets the bones move smoothly.
- Joint capsule: surrounds the joint and holds the synovial fluid in.
- Ligaments: tough bands that join bone to bone and keep the joint stable.
- Tendons: join muscle to bone so the muscle can pull on the bone (part of the wider joint, though strictly connecting muscle).
Movements at joints
You need the correct terms for joint movement.
| Movement | What it means | Example |
|---|---|---|
| Flexion | Decreasing the angle at a joint (bending) | Bending the elbow in a biceps curl |
| Extension | Increasing the angle at a joint (straightening) | Straightening the knee to kick |
| Abduction | Moving a limb away from the midline | Raising the arm out to the side |
| Adduction | Moving a limb towards the midline | Bringing the arm back to the body |
| Rotation | Turning a bone around its own axis | Turning the arm at the shoulder |
At the ankle, two extra terms apply: plantarflexion (pointing the toes down, as in a jump take-off) and dorsiflexion (pulling the toes up towards the shin).
Why this matters
The skeleton works with the muscular system to produce movement, because muscles pull on bones at the joints. The bones also act as the levers analysed in the movement analysis topic, and weight-bearing exercise has long-term effects on bone density covered under the effects of exercise.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style4 marksDescribe four functions of the skeletal system.Show worked answer →
A 4-mark question: one mark for each correct function.
The skeleton supports the body and gives it shape, holding us upright. It protects vital organs, for example the cranium protects the brain and the ribs protect the heart and lungs. It allows movement by providing a system of bones for muscles to pull on at the joints. It produces blood cells in the bone marrow of certain bones. Other valid functions are storing minerals such as calcium, and providing attachment points (anchorage) for muscles.
Markers reward any four correct functions, ideally with a brief example such as the cranium protecting the brain.
WJEC style4 marksName the type of joint at the shoulder and at the knee, and state the movements possible at each.Show worked answer →
A 4-mark question: a mark for each joint type and a mark for the movements at each.
The shoulder is a ball and socket joint. It allows a wide range of movement: flexion and extension, abduction and adduction, and rotation (and circumduction), so the arm can move in many directions.
The knee is a hinge joint. It allows movement in one plane only: flexion (bending) and extension (straightening). Markers reward the correct joint type and the correct movements, with credit for using the proper terms such as flexion and extension.
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Sources & how we know this
- WJEC GCSE Physical Education specification (from 2016) — WJEC (2016)