Joints are the connections between the bones of the skeleton that provide different types of movements. Joint surfaces are typically separated by a gap, covered with synovial membrane and articular bag.
Each joint has articular surfaces, most often covered with hyaline cartilage, a joint capsule and an articular cavity containing a small amount of synovial fluid.
The joints are located in the skeleton where distinct movements occur: flexion and extension, abduction and adduction, pronation and supination, rotation.
All joints are divided into simple, formed by two articular surfaces, and complex, consisting of several simple bone surfaces.
In addition, joints are classified according to their functions:
1. Uniaxial joints:
2. Biaxial joints:
3. Multi-axis joints: