A "flexor" is a type of muscle that helps bend a joint in the body. When a flexor contracts, it pulls on the bones it is attached to, causing the angle between the bones to decrease. Common examples of flexor muscles include the biceps in the upper arm and the hamstrings in the back of the thigh. Flexors are essential for many everyday movements, such as lifting objects, walking, and sitting down. They work in opposition to extensor muscles, which straighten joints. Proper functioning of flexors is crucial for maintaining mobility and performing physical activities effectively.