Stabilizes distal radioulnar joint
Cushions ulnar head and lunate
Central portion is avascular
Components:
Articular disc = triangular fibrocartilage
Triangular ligament
Meniscus homolog
Radioulnar ligaments: Volar and dorsal
Volar ulnolunate ligamrent
Ulnotriquetral ligament
Ulnar collateral ligaments
Tendon of extensor carpi ulnaris
Triangular fibrocartilage:
Situated on horizontal surface of ulnar head
Radial attachment: prominance of sigmoid notch distally on radius
Ulnar attachment: broader disk, base of ulnar styloid process and adjacent ulnar fovea thru upper and lower lamina
Centre is thin and the thick volar and dorsal aspects are called radioulnar ligament
2-3 times thicker on ulnar side
Supplied by ulnar and posterior interosseous branches
Central and radial sides are relatively avascular
Radioulnar ligaments:
Thickened volar and dorsal aspects of fibrocartilage
Meniscus homologue:
Between ulna and triquetrum
Common origin with fibrocartilage
Inserts into ulnar border of triquetrum
Shares common origin with TFC
Attached to synovial lining of the medial wrist joint
Extends to triquetrium and base of 5th metacarpal
Connects with ECU sheath
Can be divided into:
1. styloid component: ulnar styloid to ECU, further divided into fibrous ans vascular parts
2. collateral component: no high signal intensity between ECU tendon and meniscus homologue.
3. distal insertion: to ulnar aspect of the triquetrum and also hamate
Prestyloid recess can be narrow, wide or with no recess.
Volar ulnolunate and ulnotriquetral ligaments:
Arise from mid third of fibrocartilage and insert into volar aspects of lunate and triquetral bones respectively
They both together form anterior band of triquetral sling
Dorsal radiotriquetral ligament:
Forms posterior band of triquetral sling
From posteromedial aspect of radius to dorsal surface of triquetral proximally
ECU tendon sheath:
Merges with dorsal triangular ligament and forms posteromedial margin of TFCC
