Movements in synovial joints. These can be very extensive the shoulder joint being particularly free and able to move around three axes. Various schemes of classification of synovial joints have been used and will be found in different textbooks. Complexity Many joints possess only two articular surfaces and are therefore simple. Usually one surface is convex or larger than the other and termed male.
Complex joints have an intracapsular disc or menisci.
One which moves in two planes is biaxial, one which moves in three is triaxial. A ball and socket is multiaxial, but is equivalent to a triaxial as it has three degrees of freedom i.e. all movements can be reduced to XYZ axes. This is the best classification as regards understanding what is going on. All above classifications are approximations and have holes in them which fit uneasily. First classify joint movement.