The Forearm Acts as a Third-Class Lever During Flexion of the Elbow

Question

The forearm acts as a third-class lever during flexion of the elbow.

Accepted Answer

During flexion of the elbow, the biceps brachii muscle applies an effort force on the radius bone (where its tendon attaches) to move the forearm (load) towards the upper arm. The fulcrum is the elbow joint. Since the effort force is applied between the fulcrum and the load, this serves as an example of a third-class lever.