Radioulnar Joints

 

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• There are three radioulnar joints.
• The proximal radioulnar joint formed between the head of the radius and ulna (radial notch of the ulna).
  • This joint is a synovial, uniaxial, pivot joint.
• The middle radioulnar joint between the shafts of the radius and ulna, united by an interosseous membrane.
  • This joint is a fibrous joint.
• The distal radioulnar joint between the distal ends of the two bones (head of the ulna and the ulnar notch of the radius).
  • This joint is a synovial, uniaxial, pivot joint.
• The radioulnar joints allow:
  • pronation and supination of the forearm.

 

NOTES:

1. Pronation and supination of the forearm are not motions at the elbow joint, nor are they motions at the wrist joint. They are motions between the radius and ulna at the radioulnar joints.
2. Pronation and supination of the forearm are usually open-chain joint actions in which the radius moves around the ulna.
3. There is also an interosseous membrane between the two bones of the (lower) leg: the tibia and fibula.