Flexion is the bending movement in a joint in which the angle between the bones involved decreases. The term derives from the Latin flectere, "to bend".
Examples are bending the elbow, drawing the knee towards the abdomen or tilting the head forwards. The muscles performing the movement are called flexors, for example the biceps brachii for elbow flexion or the hamstrings for knee flexion. The functional counterpart is extension.