Synovial joints
What are they? The synovial joints are the fully mobile joints in the human body and include six types according to how the bones move against each other: the hinge, pivot, ball-and-socket, saddle, condyloid, and plane (or gliding) joints.
The joints, or combinations of joints, are commonly known as the:
Knees (condyloid, saddle - known as bicondyloid)
Elbows (hinge)
Ankles (saddle)
Wrists (saddle, condyloid, and pivot)
Toe knuckles (hinge)
Feet (plane)
Finger knuckles (hinge)
Thumb (saddle)
Hips (ball and socket)
Shoulders (ball and socket, plane)
Neck (pivot)
Jaw (also called the TMJ, bicondyloid)
Gross fact: Synovial joints are the most common joint in the human body
What is it? A synovial joint, regardless of the movement it allows, is contained within a joint capsule, or articular capsule. A fibrous sheath of connective tissue that surrounds the synovial space here the two bones (and articular cartilage on the ends) meet. The capsule is lined by the synovial membrane, which secretes synovial fluid. This lubricates the joint movement and nourishes the cartilage.
Depending on how the joint moves and the ligaments and tendons are attached, there may be a second fluid-filled membrane, the bursa. Its presence is to prevent friction between all of the moving parts. There would also be a meniscus, or articular pad, to cushion between the bone ends. An example of this type of complex configuration is the knee joint.
For more information:
Anatomy & Physiology of Synovial Joints
Medical Gross Anatomy - Introduction to Joints
StatPearls - Joint Anatomy