07 Third: joints
A joint is the place where two bones meet. There are three types:
1Fibrous
Description
- Bones are fused by fibrous tissue; with age the fibrous tissue turns into bone
Movement
- None (immovable)
Example
- The sutures between skull bones (serrated edges interlock)
2Cartilaginous
Description
- Cartilage lies between the ends of the bones
Movement
- Very limited
Example
- Between the centra of adjacent vertebrae
3Synovial
Description
- The ends of bones are covered with smooth, transparent articular cartilage and enclosed in a capsule containing synovial fluid
Movement
- Free
Example
- Most joints of the body
Synovial joints
- represent most of the body's joints.
- The articular cartilage is delicate and smooth, so bones glide easily with little friction; the synovial fluid lubricates it and absorbs shocks (trauma), making the joint flexible and shock-resistant.
- Types:
- Hinge (limited-movement) joints: movement in one direction only, in one plane — the elbow and knee.
- Ball-and-socket (wide-movement) joints: movement in many directions — the shoulder and hip.