What are the types of joints?

Joints are usually classified via their structure or function:

  • Fibrous (immovable) – joints are held together by intervening fibrous tissue, and there is no appreciable movement. Such as bones of the cranium/skull.
  • Cartilaginous (slightly movable) – the opposed bony joints are covered with hyaline cartilage and are either connected to each other by a broad flattened disc of fibrocartilage, or are united by an interosseous ligament. This connection allows for a limited amount of movement, such as joints between vertebral bodies.

  • Synovial (freely movable) – these joints are further classified according to the kind of motion permitted in them. There are certain characteristics common to synovial joints:

    • the contiguous (adjacent/neighbouring) bony surfaces are covered with articular cartilage and are not attached to one another
    • there is a joint cavity

    • the joint is completely surrounded by an articular capsule, which consists of a capsular ligament lined with a synovial membrane

    • the synovial membrane lines the whole of the interior of the joint, with the exception of the cartilage-covered ends of the articulating bones

    • additional, extra-capsular ligaments are usually present

    • due to the nature of these joints, some sort of movement is always possible