The wrist is made up of three joint articulations :
- radiocarpal: concave distal surface of the radius and the attached articular disc of the distal radioulnar joint proximally with the convex surface of the proximal carpal row (the scaphoid, lunate and triquetral bones) distally
- distal radioulnar: ulnar notch of the distal radius with the head of the ulna, united by the articular disc
- midcarpal: scaphoid, lunate and triquetrum proximally with the trapezium, trapezoid, capitate and hamate distally
Movements at the condyloid radiocarpal joint of the wrist include :
- primary: flexor carpi radialis and flexor carpi ulnaris
- secondary: palmaris longus, abductor pollicis longus, flexor digitorum superficialis and flexor digitorum profundus
- adduction (ulnar deviation)
- simultaneous contraction of flexor and extensor carpi ulnaris
- abduction (radial deviation)
- the sequential occurrence of the above four movements produces circumduction
A greater proportion of the total range (60) of wrist extension occurs at the radiocarpal joint . In contrast, a greater proportion of the total range (80) of wrist flexion occurs at the midcarpal joint, which is also the primary joint involved in wrist adduction and abduction .
The wrist joint has intrinsic and extrinsic stabilizing structures .
- lunotriquetral ligament
- scapholunate ligament complex
- triangular fibrocartilage complex
- volar radioulnar ligament
- volar radiocarpal ligaments
- volar ulnocarpal ligaments
- dorsal ligaments
A two-layered synovial capsule envelops the radiocarpal joint, attaching proximally to the radius and ulna, and distally to the carpal bones. The joint capsule thickens to form palmar, dorsal and collateral ligaments .
Arterial supply of the wrist is via the palmar and dorsal carpal arches .
- palmar carpal arch
- dorsal carpal arch
- supplied by palmar carpal branches of the radial and ulnar arteries
- reinforced by the anterior interosseous artery, alongside penetrating deep branches of the deep palmar arch
Innervation of the wrist is via the anterior interosseous nerve (arising from the median nerve), posterior interosseous nerve (arising from the radial nerve), and the deep and dorsal branches of the ulnar nerve .
- ulnar variance
- lunate morphology
- carpal boss
- carpal coalition
- bifid median nerve
- persistent median artery of the forearm
- extensor digitorum brevis manus