A saddle joint is a type of synovial joint that allows movement in two planes, providing a greater range of motion than a hinge joint. The surfaces of the bones in a saddle joint are shaped like a saddle, with one bone having a concave surface and the other a convex surface. This unique structure enables the joint to flex, extend, and move side to side. One of the most well-known examples of a saddle joint is the joint at the base of the thumb, known as the carpometacarpal joint. This joint allows for the thumb's wide range of motion, which is essential for grasping and manipulating objects. Saddle joints are important for various activities that require fine motor skills.