A saddle joint is a type of synovial joint that allows movement in two planes, providing greater flexibility than a hinge joint. It is characterized by two bone surfaces that are shaped like a saddle, with one bone fitting into the concave surface of the other. This unique structure enables a range of motion, including flexion, extension, abduction, and adduction. One of the most well-known examples of a saddle joint is the joint between the trapezium bone in the wrist and the first metacarpal bone of the thumb. This joint allows the thumb to move in various directions, making it essential for grasping and pinching objects.