Download Muscles work in pairs

Muscles work in pairs
A muscle can only pull. It cannot push. This means that
you need to have different muscles to bend your arm
and straighten it.
Muscles therefore have to work in pairs.
Straightening your arm
tendon
biceps
triceps
tendon
The triceps contracts to straighten the arm , while the biceps
relaxes.
Raising
The forearm is raised by
pulling on the biceps, and
relaxing the triceps.
© Diagram Visual Information Ltd.
Lowering
The forearm is lowered by
pulling on the triceps and
relaxing the biceps.