Joint, joint stability..

Joint   The point at which two bones or elements of a skeleton connect and may allow motion. Most joints are composed of cartilage, joint space, fibrous capsule, synovium, and ligaments.

Joint stability   The capacity of a joint to return to it's "normal" position, remaining consistent and steady. Joints remain stable due to the resting tension of the deep (shunt) muscles that act to hold one bone against the next. As each joint has specific motions that it is designed to do, these deep shunt muscles are also important in guiding the joint through the proper ranges of motion. One common example of a joint stability issue occurs in a whiplash injury. The high degree of force imparted on the neck can damage these deep muscles and prohibit them from doing their job. As a result of their failure, the neck joints become unstable allowing the joints to move in an unnatural way potentially causing further discomfort. See: muscles (deep stabilizers) and ligament for more.