Boardworks Ltd Types of Synovial Joint

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1 1 of 37 Types of Synovial Joint

2 Definition: 2 of 37

3 3 of 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 membrane Knee

4 Examples of Synovial Joints Hip Joint Elbow Joint 4 of 37 This joint can be moved in the following ways: Bend Straighten Circle Move away from the body Move towards the body This joint can be moved in the following ways: Bend Straighten

5 5 of 37 Shoulder Joint Knee Joint This joint can be moved in the following ways: Bend Straighten Circle Move away from the body Move towards the body This joint can be moved in the following ways: Bend Straighten

6 6 of Hinge Joints Hinge joints work like a hinge on a door. They can only move in two directions, e.g. the knee and elbow joints.

7 7 of Ball and Socket Joints Ball and Socket joints are the most moveable joints in the body. They can move in all directions, e.g. the hip and shoulder joints.

8 8 of 37 What are the articulating bones of the following joints? Articulating = bones that form the joint: Knee Elbow Shouler Hip

9 9 of 37 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. The patella increases the leverage of the thigh muscle. Cruciate ligament Tibia Patella

10 10 of 37 The structure of the elbow joint (hinge) The elbow is another complex hinge joint. The hinge between the humerus and ulna allows the arm 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. The whole joint is encased in a synovial capsule and held together by ligaments. Ulna Ligaments Humerus Radius

11 11 of 37 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.

12 12 of 37 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. Humerus Scapula 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.

13 Movement at Synovial Joints Different types of synovial joints allow different kinds of movement. There are 6 basic types of movement that can occur at such joints: 1. Extension: Straightening or extending a limb. 2. Flexion: Bending or flexing a limb. 13 of 37 Example: the arm can be extended at the elbow. Example: the leg can be flexed at the knee.

14 14 of Abduction: Moving a limb away from the centre line of the body. 4. Adduction: Moving a limb towards the centre line of the body. Example: The leg can be moved away from the centre of the body at the hip. Example: The arm can be moved towards the centre of the body at the shoulder.

15 15 of Rotation: This is a turning or rotational movement of a limb or body part. 6. Circumduction: The ability of a limb to be moved in circles. Example: the head can be rotated at the neck. Example: the arm can move in circles at the shoulder.

16 16 of 37 What types of movement are possible at the following joints? Ball and Socket Joint: Extension Flexion Abduction Adduction Rotation Circumduction Hinge Joint: Extension Flexion Pivot Joint: Rotation

17 Joints in action 17 of 37 Image EMPICS Ltd

18 Connective tissues 18 of 37 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.

19 Tendons and ligaments 19 of 37 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.

20 Tendons and ligaments 20 of 37

21 Exam-style questions 21 of This diagram shows a cross section of the knee. a) Name bones a, b and c. b) Name substance d. c) List the types of movement possible at the knee. d) Explain the role of cartilage in the functioning of the knee. a c b d