What are the pathomechanics of carpal bones relevant to ulnar-sided wrist pain?

Updated: Nov 22, 2019
  • Author: David M Lichtman, MD; Chief Editor: Harris Gellman, MD  more...
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Answer

Answer

The stability of the carpus is not solely a result of the interlocking shapes of the carpal bones, which are held together by interosseous (intrinsic) ligaments, as well as volar, dorsal, radial, and ulnar extrinsic ligaments. Intrinsic ligaments originate and insert on the carpal bones and can be collagenous (usually found at the dorsal and volar margin of the bone) or cartilaginous (usually along the articular surface). Extrinsic ligaments cross between the carpal bones and the radius or the metacarpals. The extrinsic ligaments maintain gross alignment; the intrinsic collagenous are intermediate in maintaining alignment, and the intrinsic cartilaginous provide fine tuning.

Additional ligaments of the wrist include components of the TFCC and the transverse carpal ligament. Although the amount of stability the flexor retinaculum provides the carpus is unknown, it is believed to contribute to the maintenance of the carpal arch.

The eight bones of the carpus serve as a link between the distal radius and ulna and the metacarpals of the hand. The carpal bones have typically been described as composing two rows, as follows:

  • Proximal row - Scaphoid, lunate, triquetrum, and pisiform
  • Distal row - Hamate, capitate, trapezoid, and trapezium

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