The role of joints in enabling movement

Joints are the points where two or more bones meet, and they make movement possible throughout the body.

Joint functions in upper and lower body

• Upper body joints - These primarily enable functional movements.
• Lower body joints - These focus more on providing stability and balance.

Types of joint movements

There are eight main types of movement that occur at joints, grouped into four pairs. Each pair consists of related actions, where one movement is often the reverse of the other.

Flexion and extension

• Flexion and extension are basic bending and straightening movements.
• Flexion - This involves bending a part of the body, such as bending your arm at the elbow.
• Extension - This means straightening a part of the body, for example, straightening your arm at the elbow.

Abduction and adduction

• Abduction and adduction involve sideways movements relative to the body's centre line.
• Abduction - This is a sideways movement away from the centre of the body, for example, lifting your arm from your side.
• Adduction - This is a sideways movement towards the centre of the body.

Rotation and circumduction

• Rotation and circumduction involve turning or circular motions.
• Rotation - This is a turning movement around an imaginary line or axis. Turning your head from left to right is one example, with the imaginary line running vertically through your skull. When you turn your leg to point your feet and toes out to the side, you are rotating your leg.
• Circumduction - This occurs when the end of a bone moves in a circular path. An example is swinging your arm in a full circle at the shoulder.

Plantar flexion and dorsiflexion

• Plantar flexion and dorsiflexion are specific to the ankle joint, controlling foot positioning.
• Plantar flexion - This points the foot away from the leg. It happens, for example, when you plant your foot down to the ground while running.
• Dorsiflexion - This brings the toes closer to the shin. It's seen when you lift your foot off the ground during running.

Joint movements in activities and sports

In real activities, multiple joint movements happen simultaneously to create fluid actions. For example, during running, the hip, knee, and shoulder joints repeatedly flex and extend: the knee flexes as the leg swings backward and extends as it swings forward.

Sport-specific examples of joint movements

• Flexion - Demonstrated in a biceps curl.
• Abduction - Seen when a volleyball player raises their arms laterally to block a shot at the shoulder.
• Rotation - Occurs when a basketball player twists at the waist to pass the ball.
• Circumduction - Used by a javelin thrower during the circular arm wind-up before release.
• Plantar flexion - Performed by a gymnast pointing their toes.
• Dorsiflexion - Evident in a hurdler lifting their toes toward the shin.

The shoulder joint is particularly versatile, capable of flexion, extension, adduction, abduction, and rotation.