why can our elbow not move backwards

The reason our elbow cannot move backwards is because the elbow joint is a hinge joint. This type of joint functions like the hinges of a door, allowing movement only in one direction—specifically flexion (bending) and extension (straightening). The bones forming the elbow joint (humerus, radius, and ulna) are arranged so that they permit movement in this single plane. Additionally, ligaments and the bony structure, such as the olecranon process of the ulna, act as physical stops that prevent backward movement, providing stability and preventing hyperextension. This biomechanical design ensures efficient function and stability in activities like lifting and pushing, but restricts the elbow from moving backwards.