Which type of joint is predominantly uniaxial and allows only flexion and extension?

A hinge joint is predominantly uniaxial, allowing movement primarily in one plane, specifically flexion and extension. This joint structure resembles that of a door hinge, which only allows it to open and close along one axis. Examples of hinge joints in the human body include the elbow and the knee, which only allow bending and straightening movements.

In contrast, ball and socket joints enable a greater range of motion, including rotation, and can move in multiple axes, making them multiaxial rather than uniaxial. Condyloid joints, such as those found in the wrist, permit movements in two planes (flexion/extension and abduction/adduction) and allow for some rotation as well. Plane joints allow sliding movements and do not restrict motion to a single plane, which means they can accommodate a variety of movements but are also not uniaxial.

Thus, the hinge joint’s restriction to flexion and extension clearly identifies it as the correct answer in relation to the question.