Upper limb
Triangular fibrocartilage complex (TFCC / Ulnocarpal disc)
Complexus fibrocartilagineus triangularis (TFCC / Discus articularis ulnocarpalis)
- Origin
- Base of ulnar styloid process and fovea of the ulna
- Insertion
- Ulnar notch of the distal radius, triquetrum, lunate, and base of 5th metacarpal
- Function
- Primary stabilizer of the distal radioulnar joint (DRUJ) and major shock absorber of the ulnar wrist (transmits 20% of axial hand load)
- Innervation
- Dorsal sensory branch of ulnar nerve and posterior interosseous nerve (vascularized in outer 15–20% rim only)
- Movement & chain
- Accommodates pronation/supination pivot and ulnar deviation of the wrist
- Palpation
- Palpable within the ulnar fovea (between ulnar styloid and FCU tendon)
- Clinical
- TFCC tear (Palmer classification type 1 traumatic vs type 2 degenerative); ulnar impaction syndrome (positive ulnocarpal stress test); DRUJ instability.
- Segmental innervation
- C7–C8
- In clinical practice
- Fovea sign testing, WristWidget or dynamic splinting, and arthroscopic TFCC repair
- Region in the model
- Upper limb