What are the functional classes of joints?

The functional classification of joints is determined by the degree and range of movement the joint allows. The three functional categories for joints are synarthrosis, amphiarthrosis, and diarthrosis. A synarthrosis joint (from the Greek syn, meaning “together,” and arthrosis, meaning “articulation”) is immovable. An amphiarthrosis joint (from the Greek amphi, meaning “on both sides”) is slightly movable. A diarthrosis joint (from the Greek dia, meaning “between”) is a freely movable joint.