Joints 1 Joints

What you will learn about Joints 2 What you will learn about in this topic: Definition of a joint Types of joints Cartilage Synovial joints Ligaments Inflammatory cascade

Joints 3 Learning objectives By the end of this presentation you should be able to: Understand how synovial joints work Describe the different joints of the body Explain how a joint works and the importance of them when dancing

Joints 4 Definition of a joint A joint is the place where two or more bones meet. There does not have to be movement at a joint, but where there is, it is more significant to the actions of a dancer.

Three types of joint There are three types of joint In the body. Joints 5 Three types of joint There are three types of joint In the body. They differ according to how much movement they allow. Immovable joints Slightly movable joints Freely movable joints

Immovable joints are fixed so there is no movement at the joint. Any place where the bones are fused together is an immovable joint; for example, the crown of the cranium and the coccyx.

Joints 7 Slightly movable joints have gaps between the bones, which allow a small amount of movement. These gaps are usually filled with cartilage. Examples include the bones of the vertebral column and the joint of the ribs and the sternum.

Examples include the joints at the wrist, hip and knee. Freely movable joints are designed for movement. Keeping them in good order is essential to a healthy active life, and are most important to the sportsperson. Examples include the joints at the wrist, hip and knee.

Examples of joints Pivot In the neck – rotates and tilts the head – assists the rotation of the body.

In the arm – flexing and extending with a slight amount of rotation. Joints 10 Hinge In the knee – extends and flexes – tucks knees for style and aerodynamics. In the arm – flexing and extending with a slight amount of rotation.

In the shoulder – full range of movement. Joints 11 Ball and socket In the shoulder – full range of movement. In the hip – full range of movement.

In the ankle – forward and back with slight sideways movement. Joints 12 Gliding In the ankle – forward and back with slight sideways movement.

Joints 13 Condyloid/gliding In the wrist – moves forward and backwards with some slight sideways movement.

Joints 14 Cartilage Cartilage acts as a shock-absorber. It protects the bone, acts as a cushion and provides almost friction-free movement in a joint. It is a smooth, sheet-like coating, present at the end of the articulating surfaces of bone and forms a barrier between the bones, stopping them wearing each other away.  

Joints 15 This is especially important in activities like long-distance running, where there is continued use of the knee joint. If the cartilage was not there, pain would occur at the joint due to the friction of the bones rubbing together.

Joints 16 Cartilage damage is common in sportspeople/dancers. A frayed cartilage decreases the efficiency of the joint and is extremely painful.

Joints 17 Synovial joints Synovial joints are the most movable joints in the body.

Joints 18 Synovial fluid acts as packing, preventing friction between the moving parts and lubricating the joint. Like oiling the chain of a bike or putting oil in the car, synovial fluid allows all of the parts to move against each other smoothly. Synovial fluid also keeps the joint free from infection.

The fluid is produced in the synovial membrane. Joints 19 The fluid is produced in the synovial membrane. The synovial capsule is a tough fibre that surrounds the joint holding the fluid in place.

Joints 20 Ligaments The stability of a joint relies on the strength of the ligaments – tough elastic fibres that attach bone to bone – and on the muscles supporting the joint. Running, stopping and changing direction all put pressure on the joint. If the ligaments are stretched too far, they tear and the joint dislocates.

Joints 21 Inflammatory cascade Inflammation of joints can occur after injury or short-term overuse. After an injury there is a series of events called the inflammatory cascade…

Injury Pro-inflammatory hormones triggered Joints 22 Injury Pro-inflammatory hormones triggered Call out for white blood cells to clean up the damage and clear infection Causing the area to go red  Leading to swelling Pain occurs

To avoid inflammation, wear appropriate attire to prevent injury. Joints 23 A healthy joint will react to injury when required. The inflammatory cascade will do its job then disappear. If it persists then it is a more chronic condition. An unhealthy joint will not be able to turn off the immune system and so will appear red and sore without reason. To avoid inflammation, wear appropriate attire to prevent injury.

Joints 24 Task Choose a dance style and explain how four different joints are used. Describe how each of the joints helps to produce movement in the chosen sport. Teacher’s notes Lower-ability students could be asked to use the knee, shoulder, hip and elbow as their examples.

Question 1. Which of the following best describes a joint? Joints 25 Question 1. Which of the following best describes a joint? A place where bones are close Where several bones and muscles meet allowing movement Where the production of movement occurs Where two or more bones meet but where there is not necessarily movement Teacher’s notes Answer is 1D.

What you have learnt in this topic: Joints 27 What you have learnt in this topic: Definition of a joint Types of joints Cartilage Synovial joints Ligaments Inflammatory cascade

Learning objectives You should now be able to: Joints 28 Learning objectives You should now be able to: Understand how synovial joints work Describe the different joints of the body Explain how a joint works and the importance of them in dance