Superior Radioulnar Joint

• Joint classification:

  Synovial pivot joint
• Axis of movement:

  Vertical
• Articular Surfaces:

  • Head of radius: oval shaped, lined with hyaline cartilage

  • Radial notch on ulna: creates 1/5 of ring, lined with hyaline cartilage

  • Annular ligament : creates 4/5 of fibro-osseous ring, lined with fibrocartilage
• Joint Capsule:

  Extensive, shared with elbow
• Synovial membrane:

  Hangs as fold below annular ligament - allows for rotation of radius
• Annular Ligament:

  • Creates 4/5 of ring

  • Strong and flexible allowing the oval head to rotate freely

  • Attached to anterior and posterior margins of radial notch

  • Superior support is provided by radial collateral ligament (ligament blends with annular ligament & margins of the radial notch)

  • Upper part is lined with fibrocartilage continuous with hyaline cartilage of radial notch

  • Lower part is lined with synovial membrane

  Action: Prevents displacement of radial head and stabilises joint
• Quadrate Ligament:

  From: Lower border of radial notch of the ulna

  To: Adjacent medial surface of neck of radius proximal to radial tuberosity. Fibres run in a crisscross orientation meaning that in any position of pronation or supination some fibres are under tension. There is then an overall constant tension in ligament in all positions

  Action: Limits both pronation and supination
• Movement: rotation of head of radius within fibro-osseous ring

  Limited by: tension in quadrate ligament