Types of Joints

This lesson covers the four types of synovial joints as required by the Edexcel GCSE PE specification (1PE0 — Topic 1: Applied Anatomy and Physiology). The Edexcel specification requires you to know hinge joints, ball-and-socket joints, pivot joints, and condyloid joints — this is more joint types than some other exam boards, so you must understand all four clearly.

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Overview of the Four Joint Types

graph TD
    A["Edexcel Synovial Joint Types"] --> B["Hinge Joint"]
    A --> C["Ball and Socket Joint"]
    A --> D["Pivot Joint"]
    A --> E["Condyloid Joint"]
    B --> B1["Knee, Elbow, Ankle"]
    C --> C1["Shoulder, Hip"]
    D --> D1["Neck<br>(atlas/axis)"]
    E --> E1["Wrist"]

    style A fill:#4a90d9,color:#fff
    style B fill:#e67e22,color:#fff
    style C fill:#27ae60,color:#fff
    style D fill:#9b59b6,color:#fff
    style E fill:#c0392b,color:#fff

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1. Hinge Joint

A hinge joint works like a door hinge — it allows movement in one plane only (forwards and backwards). It allows flexion and extension as the primary movements. Some hinge joints also permit a small degree of other movement.

Examples

Joint	Bones Involved	Key Movements
Knee	Femur and tibia	Flexion and extension
Elbow	Humerus and ulna	Flexion and extension
Ankle	Tibia, fibula, and tarsals	Plantarflexion and dorsiflexion

Structure

At a hinge joint, the convex (rounded) surface of one bone fits into the concave (hollow) surface of another bone. Strong ligaments on either side of the joint prevent sideways movement, restricting movement to one plane.

Sporting Examples

• Kicking a football — the knee extends (hinge joint) as the quadriceps contracts and the hamstrings relax. The movement is flexion followed by extension.
• Bicep curl — the elbow flexes (hinge joint) as the biceps contracts to lift the weight.
• Running — push-off — the ankle plantarflexes (hinge joint) as the gastrocnemius contracts to push the foot down and propel the body forward.

Exam Tip: The ankle is classified as a hinge joint for Edexcel GCSE PE and allows plantarflexion (pointing the toes down) and dorsiflexion (pulling the toes up). Make sure you use these specific terms rather than "flexion" and "extension" when referring to the ankle.

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2. Ball-and-Socket Joint

A ball-and-socket joint allows the greatest range of movement of all joint types. The ball-shaped head of one bone fits into the cup-shaped socket of another bone. This allows movement in all planes and in all directions.

Examples

Joint	Bones Involved	Key Movements
Shoulder	Humerus (ball) and scapula (socket)	Flexion, extension, abduction, adduction, rotation, circumduction
Hip	Femur (ball) and pelvis (socket)	Flexion, extension, abduction, adduction, rotation, circumduction

Structure

• The ball is the rounded head of the humerus (at the shoulder) or the femur (at the hip).
• The socket is the glenoid cavity of the scapula (at the shoulder) or the acetabulum of the pelvis (at the hip).
• The shoulder has a shallower socket than the hip, which gives it a greater range of movement but makes it less stable and more prone to dislocation.
• The hip has a deeper socket, making it more stable but with a slightly smaller range of movement.

Sporting Examples

• Bowling in cricket — the shoulder allows circumduction (a full circular movement) of the arm as the bowler delivers the ball.
• Star jump — the hip and shoulder both abduct and adduct as the arms and legs move out and back.
• Breaststroke in swimming — the hip abducts and adducts as the legs perform the frog kick, while the shoulder flexes and extends during the arm pull.
• Goalkeeper reaching for a ball — the shoulder allows rotation, abduction, and extension to stretch for the save.

Exam Tip: Remember that ball-and-socket joints allow all six movements (flexion, extension, abduction, adduction, rotation, circumduction). Hinge joints only allow movements in one plane. This is a common comparison question in the Edexcel exam.

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3. Pivot Joint

A pivot joint allows rotation only — one bone rotates around another. The Edexcel specification requires you to know the pivot joint at the neck (between the atlas and axis vertebrae — the first two cervical vertebrae).

Example

Joint	Bones Involved	Key Movement
Neck	Atlas (C1) and axis (C2) cervical vertebrae	Rotation (turning the head left and right)

Structure

At the pivot joint in the neck, the atlas (C1) vertebra sits on top of the axis (C2) vertebra. A bony projection from the axis (called the odontoid process or dens) sticks up through the atlas, and the atlas rotates around it — like a ring spinning on a peg.