Wrist Joint

Question 1

Articulating surfaces

Answer 1

Distally - proximal carpal bones (except pisiform)

Proximally - distal end of radius and articular disc

Question 2

Neurovascular supply

Answer 2

Dorsal and palmar carpal arches (derived from ulnar and radial arteries)
Anterior interosseous branch of medial nerve
Posterior interosseous branch of radial nerve
Deep and dorsal branches of ulnar nerve

Question 3

Stability

Answer 3

Dual layered joint capsule

4 ligaments provide stability

Question 4

Ligaments

Answer 4

• Palmar radiocarpal - palmar side of hand, from radius to both rows of carpal bones, ensures hand follows forearm during supination
• Dorsal radiocarpal - dorsal of hand, from radius to both rows of carpal bones, ensures hand follows forearm in supination
• Ulnar collateral - from ulnar styloid process to triquetrum and pisiform, prevents excessive lateral joint displacement
• Radial collateral - from radial styloid process to scaphoid and trapezium, prevents excessive lateral joint displacement

Question 5

Movements

Answer 5

Flexion - flexor carpi ulnaris/radialis, flexor digitorum superficialis
Extension - extensor carpi radialis longus/brevis, extensor carpi ulnaris, extensor digitorum
Adduction - extensor carpi ulnaris, flexor carpi ulnaris
Abduction - abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus/brevis

Question 6

Scaphoid fracture

Answer 6

Scaphoid takes most force in blow to wrist (fall on outstretched hand)
Blood supply runs distal -> proximal, fracture disrupts supply to proximal portion, emergency -> failure to revascularise = avascular necrosis and future arthritis
Sign - tenderness in anatomical snuffbox

Question 7

Anterior dislocation of lunate

Answer 7

Fall on dorsiflexed wrist -> lunate forced anteriorly -> compresses carpal tunnel -> carpal tunnel syndrome symptoms (paresthesia in sensory distribution of median nerve, weakness of thenar muscles)
Lunate can also undergo avascular necrosis -> immediate clinical attention required

Question 8

Colles’ fracture

Answer 8

Most common pathology of wrist
Fall on outstretched hand
Radius fractures, distal fragment displaced posteriorly
Ulnar styloid process can also be damaged and is avulsed in most cases
‘Dinner fork deformity’