1. Joints and their classifications

2. Joint movement – what are joints?
A joint is a place where two or more bones meet.
Without joints, our bodies would not be able to move.
Joints, along with the skeleton and muscular system, are responsible for the huge range of movement that the human body can produce.
There are several different types of joint, each producing different types and amounts of movement.
Image © 2006 Jupiterimages Corporation

3. Different types of joint
There are 3 different types of joint:
1. Immovable (or fixed) joints
synarthroses
2. Slightly movable joints
amphiarthroses
3. Movable (or synovial) joints
diarthroses

4. 1. Fixed or immovable joints
There are fewer than 10 immovable joints in the body.
They are sometimes called fibrous joints because the bones are held together by tough fibres.
Immovable joints can be found in the skull and pelvis, where several bones have fused together to form a rigid structure.
Fixed or immoveable joints such as those of the flat bones of the skull allow very slight movement. Movement is necessary for expansion of the soft tissues of the brain and to absorb some of the force of impacts – if joints were completely fixed they might crack with an impact such as a blow on the head.

5. 2. Slightly movable joints
Slightly movable joints are sometimes called cartilaginous joints.
The bones are separated by a cushion of cartilage. The joints between the vertebrae in the spine are cartilaginous joints.
The bones can move a little bit, but ligaments stop them moving too far. This is why we can bend, straighten and rotate through the back, but not too far.
bone
cartilage
bone
The structure of the spinal column necessitates slightly moveable joints. Why the sacrum and coccyx areas of the spine are fixed joints? Answer: for attachment of lower back muscles (Sacrum) and balance (coccyx).
ligaments

6. 3. Freely movable or synovial joints
90% of the joints in the body are synovial joints. They are freely movable.
Synovial joints contain synovial fluid which is retained inside a pocket called the synovial membrane. This lubricates or ‘oils’ the joint.
All the moving parts are held together by ligaments.
These are highly mobile joints, like the shoulder and knee.
Synovial fluid
Synovial joints offer a wide range of sporting movement.
Synovial membrane
Knee

7. Connective tissues
Connective tissues are vital to the functioning of joints. There are 3 types of connective tissue:
Ligaments are tough, elastic fibres that link bones to bones.
Tendons connect muscles to bones.
Ligaments – are elastic allowing the bones to twist and turn – however if the stress on the ligaments is too great or forceful they can be overstretched or torn (like an elastic band) and will cause injury to the sportsperson. The cruciate ligaments of the knee are commonly injured in sport.
Cartilage – is found at the ends of bones and is smooth and slightly flexible providing shock absorption and reducing friction for ease of movement between bones/ joints
Tendons – are less elastic and join bone to muscle – like ligaments they can be damaged by the stress and strain of excessive movements – the Achilles tendon that joins the foot to the calf muscle (gastrocnemius) can be injured through repeated jumping movements.
Cartilage prevents the ends of bones rubbing together at joints. Its slippery surface also helps to lubricate the joint.

8. Ligaments and tendons are strengthened by training.
Tendons and ligaments
Ligaments are responsible for holding joints together. They prevent bones moving out of position during the stresses of physical activity.
If they are pulled or twisted too far by extreme physical movements, ligaments can tear and the joint may dislocate.
Tendons anchor muscles to bones, allowing the muscles to move the skeleton. Tendons are not very elastic – if they were, then the force produced by muscles would be absorbed instead of creating movement.
Tendons can also be torn if subjected to too much force.
Ligaments and tendons are strengthened by training.

9. Freely movable (synovial) joints
The joint capsule is an outer sleeve that protects and holds the knee together.
The synovial membrane lines the capsule and secretes synovial fluid – an oil like liquid which lubricates the joint, allowing it to move freely.
Synovial fluid
Femur
Synovial membrane
Cartilage
Tibia
Joint capsule
Smooth coverings of cartilage at the ends of the bones stops them rubbing together and provide some shock absorption.
Ligaments hold the bones together and keep them in place.

10. Types of synovial joints
In ball and socket joints, the rounded end of one bone fits inside a cup-shaped ending on another bone.
Ball and socket joints allow movement in all directions and also rotation. The most mobile joints in the body are ball and socket joints.
Examples: Shoulders and hips.
Hip
Describe ball and socket joints at the hip and shoulder. Think of the movements possible at these joints. How do they help during sport?

11. Types of synovial joints
Pivot joints have a ring of bone that fits over a bone protrusion, around which it can rotate.
These joints only allow rotation.
Atlas
Examples: The joint between the atlas and axis in the neck which allows you to shake your head.
Axis

12. Types of synovial joints
In saddle joints, the ends of the two bones fit together in a special way, allowing movement forwards and backwards and left to right, but not rotation.
Examples: The thumb is the only one.
Hinge joints – as their name suggests – only allow forwards and backwards movement.
Examples: The knee and elbow.
Elbow

13. Types of synovial joints
Condyloid joints have an oval-shaped bone end which fits into a correspondingly shaped bone end.
They allow forwards, backwards, left and right movement, but not rotation.
Examples: between the metacarpals and phalanges in the hand.
Gliding joints have two flat faces of bone that slide over one another.
They allow a tiny bit of movement in all directions.
Examples: between the tarsals in the ankle.

14. Synovial joints – sporting examples
During the butterfly stroke, the ball and socket joint of the shoulder allows the swimmer’s arm to rotate.
You might head a football using the pivot joint in your neck, which allows your head to rotate.
Answer:
The condyloid joints between the metacarpals and phalanges.
Swimmer image © 2006 Jupiterimages Corporation
What type of joint allows a handball player’s fingers to spread apart so that they can control the ball with one hand?
Answer:
The condyloid joints between the metacarpals and phalanges.

15. Movement Patterns
In order for us to understand sporting movements, we have to be able to label the possible movements available at a joint, using specific terms.

16. Flexion Extension Adduction Abduction
When the angle of the joint increases
When the angle of the joint decreases
Extension
Adduction
Movement towards the midline of the body
Abduction
Movement away from the midline of the body (e.g. A star jump

17. Rotation Circumduction
The limb moves in a Circle. For example this occurs at the shoulder joint during an ‘Overarm bowl in Cricket’
Rotation
The limb moves in a circular motion towards the midline of the body. For example this occurs in a ‘golf swing when driving the ball’

18. Dorsiflexion Plantar Flexion
flexion or bending toward the extensor aspect of a limb, as of the hand or foot.
Plantar Flexion
a toe-down motion of the foot at the ankle. It is measured in degrees from the 0-degree position of the foot at rest on the ground with the body in a standing position.

19. The structure of the elbow joint (hinge)
Humerus
The elbow is another complex hinge joint. The hinge between the humerus and ulna allows the arm to bend (Flexion) and straighten (Extension).
The elbow also has a pivot joint between the ulna and radius which allows us to rotate (Rotation) the lower arm while keeping the upper arm still.
A gliding action occurs between the humerus and radius.
The whole joint is encased in a synovial capsule and held together by ligaments.
Radius
Demonstrate movements to the class – get them to copy your movements.
Ulna
Ligaments

20. Task…
1) Find a picture of a player in action. Paste it into a word document.
Use arrows to label the picture with each of the following joint types and what movements (flexion/adduction/ rotation etc.) are available at each Joint:
- 2 Hinge Joints
- 2 Ball and Socket Joints
- Gliding Joint
- Pivot Joint
- Saddle Joint
- Condyloid Joints
Bring picture and labelling to class on Monday
(see next slide for an example)

21. E.G. Some suggested answers:
Left elbow – involves the humerus, radius and ulna. It is a hinge joint. It is extended.
Left wrist – involves the carpals. This is a gliding joint. There is rotation.
Left hand – joint between metacarpals and phalanges. This is a condyloid joint. There is abduction and flexion on the phalanges.
Right hip – involves the pelvis and femur. This is a ball and socket joint. There is abduction.
Knees – involve the femurs, tibias and fibulas. These are hinge joints. There is flexion.