What is the elbow joint an example of?

A simple joint.

Which bones does the elbow joint connect?

The upper arm bone to the forearm bones.

What force can wear away bones when they rub against each other?

Friction.

What covers the ends of bones at a joint?

A thick layer of cartilage.

What is the function of cartilage in a joint?

It protects the ends of the bones and allows them to slide over each other.

What natural lubricant is produced in a joint?

Synovial fluid.

What is the function of synovial fluid?

It reduces friction and stops the bones rubbing together.

What are ligaments?

Strong, tough fibres that connect bones together.

What is the function of ligaments in a joint?

They connect the bones and provide joint stability.

What is the upper arm bone called?

The humerus.

Name the key structures shown in the elbow-joint diagram.

Humerus, forearm bones, cartilage, synovial fluid and ligaments.

Why must the parts of a joint be stable?

So the joint can be used without the bones separating or the joint being damaged.