Which of the following joint structures uses flexion and extension as its possible movements?

The hinge joint is characterized by its ability to allow movement primarily in one plane, which includes flexion and extension. This structure resembles the operation of a door hinge, allowing one bone to move relative to another in a straightforward manner. For example, when you bend your elbow or knee, you are utilizing the flexion and extension movements typical of hinge joints.

In contrast, ball and socket joints permit a broader range of motion, including flexion, extension, rotation, and abduction, as seen in the shoulder and hip joints. Pivot joints allow rotational movement around a single axis, such as the neck's ability to rotate the head from side to side. Finally, saddle joints enable movement in two planes (back and forth as well as side to side), like the thumb's motion. Each of these joint types offers unique movement capabilities, but only the hinge joint specializes in flexion and extension.