Why is a pair of muscles needed to operate the elbow joint?

A pair of muscles is needed to operate the elbow joint to facilitate both flexion and extension. The biceps brachii muscle contracts to bend the elbow, while the triceps brachii muscle contracts to straighten it. This antagonistic relationship allows for smooth and controlled movement, enabling various activities such as lifting and throwing. Without this pairing, the joint would lack the necessary range of motion and functionality.