Ulnocarpal Ligaments

The ulnocarpal ligaments are extrinsic ligaments that connect the ulna to the carpal bones. They can be divided into palmar and dorsal. The ulnocarpal ligaments seen on MRI all arise from the palmar and dorsal radioulnar ligaments.

Palmar

• Palmar ulnotriquetral ligament: The palmar ulnotriquetral ligament originates from the palmar radioulnar ligament and extends distally to attach to the palmar aspect of the triquetrum. Course best seen in the sagittal plane. Cross section best seen in the transverse plane.
  
  
• Ulnolunate ligament: The ulnolunate ligament originates on the radial side of the palmar radioulnar ligament, with attachments to both the ulna and radius. It extends distally to attach onto the palmar aspect of the lunate. The fibers of the radiolunotriquetral ligament make a stop on the lunate at the same insertion site. Course best seen in the sagittal plane. Cross section best seen in the transverse plane.
  
  
• Ulnocapitate ligament: The ulnocapitate ligament is not seen on MR images, so we'll pretend it doesn't exist.

Dorsal

• Dorsal ulnotriquetral: The dorsal ulnotriquetral ligament originates from the dorsal radioulnar ligament and travels distally to attach onto the dorsal aspect of the triquetrum together with the fibers of the dorsal radiotriquetral ligament. Course best seen in the sagittal plane. Cross section best seen in the transverse plane.

References

Theumann NH, Pfirrmann CW, Antonio GE, Chung CB, Gilula LA, Trudell DJ, Resnick D. Extrinsic carpal ligaments: normal MR arthrographic appearance in cadavers. Radiology. 2003 Jan;226(1):171-9.