Upper limb
Scapholunate ligament
Ligamentum scapholunatum interosseum
- Origin
- Proximal margin of the scaphoid
- Insertion
- Adjoining margin of the lunate; the ligament runs as a C around the joint line, with the dorsal fibres as its strongest part
- Function
- Holds the scaphoid and lunate together as one unit, so that the proximal carpal row turns as a whole during wrist movement.
- Innervation
- Posterior interosseous nerve, with dense proprioceptive innervation
- Movement & chain
- Without this ligament the scaphoid tilts palmarly and the lunate dorsally: the two bones naturally want to move in opposite directions, and only the ligament holds them together.
- Palpation
- Move straight distally from Lister's tubercle until you feel the joint line. Press there while moving the wrist into radial and ulnar deviation; tenderness exactly at that point is the clue.
- Clinical
- The commonest carpal ligament injury, usually from a fall on the outstretched hand. Untreated it leads through SL dissociation to a predictable pattern of osteoarthritis. Watson's test provokes it.
- Segmental innervation
- Segmentally C6-C8
- In clinical practice
- Persisting radial wrist pain after a fall, with tenderness at this point and a normal radiograph, should be investigated further before loading is trained.
- Region in the model
- Upper limb