The saddle joint is a joint in which the joint surfaces of two bones are saddle-shaped, with mutual joint heads and fossae. The saddle joint has two axes of motion and can do flexion, extension, extension, retraction and circular motion along both axes. The saddle joint is a biaxial joint, which is capable of two sets of movements around two perpendicular axes of motion, as well as a circular motion, so there are fewer saddle joints in humans. The common interphalangeal joint is not a saddle joint, but a flexion garrison joint, also known as a gliding joint, which is a uniaxial joint. Usually, biaxial joints include only saddle joints and elliptical joints, while elliptical joints are mainly found in the radial carpal and atlanto-occipital joints. Therefore, the saddle joint is mainly found in the carpometacarpal joint of the thumb.