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Four important synovial joints

Four important synovial joints used in most sporting actions are the elbow and shoulder joints in the arm, and the knee and hip joints in the leg.

The elbow and knee joints are both hinge joints. A hinge joint is a type of synovial joint that works like the hinge on a door, allowing bending and straightening only.

The shoulder and hip joints are both ball and socket joints. A ball and socket joint is a type of synovial joint that allows movement in almost every direction. A ball and socket joint is made up of a round end of one bone that fits into a small cup-like area of another bone.

Elbow joint

  • Hinge joint.
  • Articulating bones are humerus, radius and ulna.
  • Allows bending (flexion) and straightening (extension).
  • Muscles which move the elbow are biceps and triceps.
Cross-section of an elbow joint, including the humerus, radius, ulna, biceps, triceps, cartilage, and joint capsule.
Figure caption,
The different components of the elbow joint that allow a hinge action

Knee joint

  • Hinge joint.
  • Articulating bones are femur and tibia (the patella is not classed as part of the joint, nor is the fibula).
  • Allows bending (flexion) and straightening (extension).
  • Muscles which move the knee are quadriceps and hamstrings.
Cross-section of a knee joint, including the femur, patella, fibula, tibia, quadriceps tendon, collateral ligament, articular cartilage and synovial fluid.
Figure caption,
The different components of the knee joint

Hip joint

  • Ball and socket joint
  • Articulating bones are pelvis and femur (head of femur is 'ball' and cup in pelvis is 'socket')
  • Allows a large range of movement in all directions
  • Many muscles are used to move the hip joint, including the gluteals
Cross-section of a hip joint, including the pelvis, femur, ligament, cartilage and synovial fluid.
Figure caption,
The different components of the hip joint

Shoulder joint

  • Ball and socket joint.
  • Articulating bones are humerus and scapula (the clavicle is not part of the shoulder joint).
  • Allows a great range of movement in all directions.
  • Many muscles are used to move the shoulder joint, including the deltoid, trapezius and latissimus dorsi.
Cross-section of a shoulder joint, including the clavicle, scapula, humerus, articular cartilage and tendon of biceps.
Figure caption,
The different components of the shoulder joint