What action is primarily associated with flexor muscles?

Flexor muscles are primarily responsible for bending joints. When flexor muscles contract, they decrease the angle between two body parts, which is most commonly observed in joints such as the knee and elbow. The action of bending the knee is a quintessential example of this function, as the flexor muscles around the knee work to move the lower leg closer to the thigh.

In contrast, options such as moving the arm or activating the buccal nerve describe functions that are not specific to flexor muscles. The movement of the arm can involve various muscle groups, including extensors and abductors, depending on the direction of the movement. Connecting two bones together refers to ligaments, which provide stability to joints but do not describe the action of muscle contraction or bending. Therefore, bending the knee clearly aligns with the primary function of flexor muscles.