Fibrous joints are connected by dense fibrous connective tissue, cartilaginous joints are connected by cartilage, and synovial joints contain a fluid-filled joint cavity. Consequently, they generally permit no or minimal movement, limited movement, and free movement, respectively.
Structure and Function
Joints are classified structurally according to the material connecting the bones and whether a joint cavity is present. Their structure determines their stability and range of motion.
| Joint type | Structure | Movement and examples |
|---|---|---|
| Fibrous | Bones are joined by dense fibrous connective tissue; there is no joint cavity. | Usually immovable or permits minimal movement. Examples include sutures of the skull and the tibiofibular syndesmosis. |
| Cartilaginous | Bones are joined by hyaline cartilage or fibrocartilage; there is no joint cavity. | Permits limited movement while providing support and shock absorption. Examples include intervertebral discs and the pubic symphysis. |
| Synovial | Bone ends are separated by a cavity containing synovial fluid. Articular cartilage covers the bone surfaces, and a joint capsule encloses the joint. | Freely movable. Examples include the knee, hip, shoulder, and elbow. |
In a synovial joint, articular cartilage reduces friction and absorbs compressive forces. The synovial membrane produces synovial fluid, which lubricates and nourishes the cartilage, while ligaments connect bone to bone and reinforce the joint. These adaptations enable movement while maintaining stability.
A common misconception is that any joint containing cartilage is cartilaginous. Synovial joints also contain articular cartilage, but they are classified as synovial because they possess a synovial cavity; in a cartilaginous joint, cartilage directly connects the bones.
IB Exam Technique
For subtopic B.1.2, compare the three joint types using three criteria: connecting tissue, presence or absence of a joint cavity, and degree of movement. If asked to explain function, link each structural feature directly to mobility, stability, friction reduction, or shock absorption rather than simply listing joint components.