Joints and their classifications P2 Joints and their classifications

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

Different types of joint There are 3 different types of joint: 1. Immovable (or fixed) joints 2. Slightly movable joints Reference to skeletal structures could be enhanced by using a skeleton or skeletal models if available. Use this presentation to remind students of the names of a range of bones. Students must be confident in naming the bones of the skeleton and their position/ location in the body. Without this understanding they will struggle to identify the bones that form joints. 3. Movable (or synovial) joints

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 – ask students why they should allow a little 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.

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 Discuss with students the structure of the spinal column and why slightly moveable joints are the most suitable type of joint for the cervical, thoracic and lumbar spine areas. Ask them why the sacrum and coccyx areas of the spine are fixed joints? Answer: for attachment of lower back muscles (Sacrum) and balance (coccyx). ligaments

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

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. Discussion of the properties of the different connective tissues would be relevant here. 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.

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.

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. Students should be able to recognise the key structures of the knee and their function. Ligaments hold the bones together and keep them in place.

Task… - Fixed or fibrous - Slightly moveable or cartilaginous Types of joints 1) Give a brief description (Up to 50 words each/also picture examples) of each of the following types of joints, and the movement available at each one - Fixed or fibrous - Slightly moveable or cartilaginous - Synovial or freely moveable 2) Label a Synovial Joint: Copy the picture of the synovial joint from the internet and label/describe it

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. Discuss the movements possible at these joints. How do they help during sport?

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

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

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.

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.

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.

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

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’

Task… 3/ 4) Find a picture of a player and label all of the 6 major synovial joints: - 2 Hinge Joints - 2 Ball and Socket Joints - Gliding Joint - Pivot Joint - Saddle Joint - Condyloid Joints The same picture, use arrows to label the various types of movement pattern occurring at each joint, E.G: Flexion, rotation, plantarflexion, circumduction etc…

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.

- 2 Ball and Socket Joints - Gliding Joint - Pivot Joint Classification of 3 joints: Fixed Slightly Moveable Synovial/Freely Moveable 1) Learners need to be able to describe all three classifications of joint and the amount of movement available at each. 2) Provide a picture and label a synovial joint. 3) Provide an example of each type of Synovial joint. 3) Movement patterns available at each joint. Types of Joint: - 2 Hinge Joints - 2 Ball and Socket Joints - Gliding Joint - Pivot Joint - Saddle Joint Condyloid Joints Movement Patterns: Flexion/ Extension Adduction/ Abduction Rotation/ Circumduction Supination/ Pronation Plantarflexion/ Dorsiflexion Inversion/ Eversion