1. Flexor Muscles: Muscles that contract or bend a limb are called flexor muscles. The process of bending or contracting a part of a flexor muscle is called flexion. For example, the biceps muscle bends the elbows or fingers
2. Extensor Muscles: Muscles that extend or spread a limb are called extensor muscles. The process of extending or spreading a part of the extensor muscle is called extension. For example, the triceps muscle extends the forearm.