Which type of joint allows for biaxial movement?

Biaxial movement refers to the ability of a joint to move in two different planes or axes. Saddle joints are a prime example of this type of joint. They allow movement along two primary axes, which include flexion and extension as well as abduction and adduction. The unique structure of saddle joints, where the articulating surfaces resemble a saddle, permits this wide range of movement.

For instance, the carpometacarpal joint of the thumb is a saddle joint, enabling the thumb to move toward and away from the palm (abduction/adduction) as well as to bend and straighten (flexion/extension). This flexibility is crucial for the intricate movements of the thumb, ultimately allowing for a stronger grip and enhanced hand functionality.

The other types of joints listed do not provide for biaxial movement to the same extent. Hinge joints, for example, primarily allow movement in one plane (flexion and extension), while pivot joints permit rotation around a single axis. Synarthrosis joints are immovable, which does not support any form of movement. Understanding the functional capabilities of each joint type helps in comprehending joint mechanics and their roles in the human body.