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Ligaments of the Thumb CMC:

1.  Beak ligament (anterior oblique)

  • Major stabilizing factor for the 1st CMC joint
  • Interconnects the palmar tubercle (beak) of the metacarpal base and the distal part of a ridge on the tubercle of the trapezium
  • Tight in abduction, extension, and opposition

2.  Ulnar collateral ligament

  • Volar and medial aspects of the CMC joint
  • Extends from the transverse carpal ligament to the palmar-medial base of 1st metacarpal

Collateral Ligaments

Stabilize the MCP joint, PIP joint, and DIP joint

What is the most common ligament injured in the thumb?

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Ulnar collateral ligament