Learning objectives
Learning objectives What we will learn in this presentation: What joints are Classifying joints as fixed, slightly moveable and freely moveable The 3 types of connective tissue and their functions The different types of synovial joint and how they are used in various sporting movements The structure of different joints Analysing joint functions in different movements How joints and flexibility are effected by physical activity and age.
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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. 2 of 37
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Different types of joint There are 3 different types of joint: 1. Immovable (or fixed) joints
2. Slightly movable joints
3. Movable (or synovial) joints
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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.
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2. Slightly movable joints Slightly movable joints are sometimes called cartilaginous joints. bone cartilage bone ligaments
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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.
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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 Synovial fluid ‘oils’ the joint. All the moving parts are held together by ligaments. These are highly mobile joints, like the shoulder and knee.
Synovial membrane Knee
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Different types of joint
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Connective tissues Connective tissues are vital to the functioning of joints. There are 3 types of connective tissue: Tendons connect muscles to bones.
Ligaments are tough, elastic fibres that link bones to bones.
Cartilage prevents the ends of bones rubbing together at joints. Its slippery surface also helps to lubricate the joint.
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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 of 37
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Tendons and ligaments
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Freely movable (synovial) joints The joint capsule is an outer sleeve that protects and holds the knee together.
Synovial fluid
The synovial membrane lines the capsule and secretes synovial fluid – a liquid Cartilage which lubricates the joint, allowing it to move freely. Smooth coverings of cartilage at the ends of the bones stops them rubbing together and provide some shock absorption.
Femur
Tibia
Synovial membrane Joint capsule
Ligaments hold the bones together and keep them in place. 11 of 37
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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.
Hip
Examples: Shoulders and hips.
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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 13 of 37
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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.
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Elbow
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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. 15 of 37
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Types of synovial joints
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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. What type of joint allows a handball player’s fingers to spread apart so that they can control the ball with one hand?
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Synovial joints – sporting examples The saddle joint allows the thumb to curl around a canoe paddle to give a firm grip. The hinge joint at the knee allows the leg to flex and extend, for example when a hurdler extends their trail leg at take-off and then flexes it as they clear the hurdle. Can you think of a sporting movement that involves the gliding joints between the tarsals? 18 of 37
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Joint movement – how do we move?
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Tasks Working with a partner: Take it in turns to demonstrate a simple sporting movement, for example performing a biceps curl or taking a step forward. Together, analyse the movement and decide what types of movement are occurring at each joint. Now take it in turns to name a joint. Ask your partner to demonstrate and name all of the movements possible at that joint. For example, the hinge joint at the elbow shows flexion, extension and slight rotation.
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The structure of the knee joint (hinge) The knee is a very large and complex joint. You need to know the details of how it works. The femur is hinged on the tibia so that the leg can be Femur bent (flexion) and straightened (extension). Cruciate ligaments bind the bones together by crossing inside the joint. Other ligaments act to stabilise the joint.
Patella
Cruciate ligament
Tibia
The patella increases the leverage of the thigh muscle. 21 of 37
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The structure of the elbow joint (hinge) The elbow is another complex Humerus hinge joint. The hinge between the humerus and ulna allows the arm Radius to bend and straighten. The elbow also has a pivot joint between the ulna and radius which allows us to rotate the lower arm while keeping the upper arm still. A gliding action occurs between the humerus and radius.
Ligaments
Ulna
The whole joint is encased in a synovial capsule and held together by ligaments. 22 of 37
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The structure of the hip joint (ball and socket)
Pelvis Femur
The hip joint is a large ball and socket joint. The head of the femur (long bone), which is shaped like a ball, fits into the socket (shaped like a cup) of the pelvis.
The bones are covered in cartilage and reinforced with ligaments.
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The structure of the shoulder joint (ball and socket) The head of the humerus is shaped like a ball and fits into the cup-shaped socket of the scapula.
Scapula Humerus
The bones are covered in cartilage and held together with ligaments. Ball and socket come apart
The shoulder joint has more freedom to move than the hip joint and is capable of a greater variety of movement. However, this means it can dislocate more easily. 24 of 37
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Sacro-iliac joint The sacro-iliac joint is ilium an example of a synovial joint, that allows little sacro-iliac movement. It allows slight rotation of the sacrum against the hip bones (ilium).
joint
sacrum
It helps to absorb some to the forces produced by activities like jumping and landing. 25 of 37
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Name the bones in these joints
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Other synovial joints
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Look at this cricketer making a catch.
Task – try to work out the movements at each joint. 27 of 37
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Wrist, fingers and ankles The wrist is more than just a hinge joint – it can perform many complex movements, including flexion, extension, abduction and adduction. The fingers can be made into a fist (flexion) or straightened (extension). The fingers can be spread (abduction) or brought close together (adduction). The ankle is another complex hinge joint. The foot can bend down and bend up. It can also slide turn out (eversion) and in (inversion), as a result of gliding action between the tarsal bones. 28 of 37
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Joint movement Joints enable us to make an extremely wide range of movements under our conscious control. The different types of joints allow us to move in many different ways and to perform many different actions. Consider this dancer. The hinge joints at her elbows and her right knee are extended. Her left knee is flexed. There is abduction at her shoulders and right hip. The spine shows extension as the head moves back. 29 of 37
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Sporting movement
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Joint and movement analysis
Analyse the joint movements involved in these two sports actions. 31 of 37
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Joints in action
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Joints and sport Joint flexibility is important in sport, especially in activities like gymnastics and diving that require extreme movements. Participants in all sports however, can benefit from the greater range of movement that comes with improved flexibility. Flexibility exercises increase the range of movement at joints. This can reduce the risk of injury and damage as the joints are more able to absorb forces. However, overstretching joints can cause injury to them.
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Joints and old age Most people’s flexibility deteriorates as they get older. This is because the connective tissues around the joints become less elastic. Flexibility exercises and extended warm-ups before exercise can help, but ultimately, it becomes harder and harder to maintain the same levels of flexibility.
Young gymnasts benefit from good flexibility.
Some people, especially older individuals, may develop arthritis – a disease that causes pain, stiffness and inflammation around joints. It is usually hereditary, but injured joints that have not healed properly can be more prone to arthritis. 34 of 37
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Exam-style questions 1. This diagram shows a cross section of the knee. a) Name bones a, b and c.
b a
b) Name substance d. c) List the types of movement possible at the knee.
d c
d) Explain the role of cartilage in the functioning of the knee. 2. Explain how age affects joint flexibility and suggest a way in which flexibility can be improved.
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Can you remember all these keywords? Joint – a place where two or more bones meet. Flexibility – the range of movement possible at a joint. Ligaments – strong, elastic fibres that join bones together. Tendons – non-elastic fibres that attach muscles to bones. Cartilage – connective tissue found at the ends of bones to protect them and enable smooth movement. Flexion – the action causing a limb to bend. Extension – the action of a joint / limb straightening. Abduction – the action of a limb moving outwards, away from the body. Adduction – the action of a limb moving in, towards the body. Rotation – the action of a limb turning around.
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