Which ligament stabilizes the radial head against the ulna and allows pronation and supination?

Which ligament stabilizes the radial head against the ulna and allows pronation and supination?

• A. Annular ligament - pronation and supination
• B. Ulnar collateral ligament
• C. Radial collateral ligament
• D. Transverse carpal ligament

Answer: (A)

The proximal radioulnar joint is a pivot joint where the radius rotates around the ulna during pronation and supination. The ring-like annular ligament encircles the radial head and attaches to the ulna on both sides, holding the radial head against the ulna while allowing smooth rotation. This setup stabilizes the radial head against translation or dislocation as you rotate the forearm. The other ligaments have different roles: the ulnar collateral ligament stabilizes the inner (medial) elbow against valgus stress, the radial collateral ligament resists varus stress on the elbow, and the transverse carpal ligament is part of the wrist region, not the elbow.

The proximal radioulnar joint is a pivot joint where the radius rotates around the ulna during pronation and supination. The ring-like annular ligament encircles the radial head and attaches to the ulna on both sides, holding the radial head against the ulna while allowing smooth rotation. This setup stabilizes the radial head against translation or dislocation as you rotate the forearm.

The other ligaments have different roles: the ulnar collateral ligament stabilizes the inner (medial) elbow against valgus stress, the radial collateral ligament resists varus stress on the elbow, and the transverse carpal ligament is part of the wrist region, not the elbow.