A joint is any place where two bones meet. Joints are grouped by the tissue that holds them together and by how freely they move.
Fibrous joints
Dense connective tissue binds the bones tightly, so these joints barely move. Examples are the skull sutures, the lower joint between tibia and fibula, and a tooth in its socket.
Cartilaginous joints
Cartilage links the bones and allows a small amount of movement. The intervertebral discs and the pubic symphysis are examples.
Synovial joints
The bone ends are separated by a fluid-filled cavity inside a capsule, so they move freely. Most limb joints, such as the shoulder, hip and knee, are synovial.
Shapes of synovial joints
Shape sets the movement: hinge (elbow), pivot (between the first two neck vertebrae), ball and socket (hip), condyloid (wrist), saddle (base of the thumb) and plane (between the small wrist bones).
| Type | Movement | Example |
|---|---|---|
| Fibrous | Little or none | Skull sutures |
| Cartilaginous | Slight | Intervertebral discs |
| Synovial | Free | Shoulder, hip, knee |
At the bedside
Joint exams focus on synovial joints because they are the ones that swell, lock and lose range. Knowing each joint's normal movement lets you spot when range of motion is reduced.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).