Synovial Joints-Saddle Joints

Saddle (a.k.a. sellar) joints are also biaxial joints, but here, the articulating surfaces are concavoconvex (one bone shaped like a saddle and the other shaped like a horse's back). These joints allow flexion, extension, abduction, adduction and circumduction. An example of a saddle joint is the carpometacarpal joint of the thumb.