General Anatomy: Joints

Diarthrosis refers to freely movable joints, which include all synovial joints.

Ball-and-socket joints (e.g., shoulder and hip) allow movement in all directions, including rotation.

Synovial fluid, produced by the synovial membrane, reduces friction between articular surfaces.

Amphiarthroses are slightly movable joints, such as intervertebral discs, where cartilage acts as a cushion.

Circumduction is a circular movement that combines flexion, extension, abduction, and adduction.

Complex joints have an intra-articular disc dividing the joint cavity, as seen in the sternoclavicular joint.

Hinge joints, such as the knee and elbow, allow movement in one plane, like opening and closing a door.

A gomphosis is a fibrous joint where a tooth fits into its socket, held by periodontal ligaments.

Adduction moves a limb toward the body's midline, as in bringing the arms to the side.