A joint is a point at which two bones make contact. It allows movement in many planes.
- Fibrous joints: Joins bones where no movement is allowed. An example of this includes the bones of your cranium (the skull).
- Cartilaginous joints: These allow slight, restricted movement. An example is the discs between the vertebrae of the spine.
- Synovial joints: These allow free movement in one or more directions. Examples include the joints of the pelvic and pectoral girdles. They also facilitate movements like standing, sitting, walking and running.
Another way of categorising joints is movable and immovable joints. Most joints in the skeleton are movable joints. Movable joints are also known as synovial joints. Synovial joints are characterised by the existence of capsules, which contain synovial fluid. The synovial fluid helps to prevent friction during movement.
There are a number of different types of synovial joints. The four main types of synovial joints include:
- Ball and socket joint: Found in structures such as the shoulder. It allows forwards/backwards, up/down and roundabout movement.
- Hinge joint: Found in structures such as the elbow. It allows the forearm to move up and down and acts like the hinge of a door.
- Pivot joint: Allows turning of the head in a rotational movement from side to side.
- Gliding joint: Found in the wrist and foot. It allows bones to slide over one another.
Activity: Movement at Joints
Joints occur where two bones meet. Different types of joints allow for different types of movements. In this activity you will need to identify the different joint types, identify where they are located in the body and describe their motion.
For each of the following joints, you need to:
- give an example of their location in the body
- describe their motion
- Fibrous joints
- Ball and socket joints
- Gliding joints
- Hinge joints
- Pivot joints