Kinesiology, NTUPT

The Wrist

Functions of the Wrist
Joint Structure of the Wrist
Kinematics of the Wrist
Muscles at the Wrist
Wrist Stability
Mechanism of Injury at the Wrist

Objectives： After studying this topic, the students will be able to

to identify the structure of the wrist, including joint type, articular shape, and the surrounding tissues
to describe joint motions occurring at the wrist, including physiological and accessory movements, muscle actions, and factors checking wrist motions
to understand the stability mechanism of the wrist and the possible mechanisms of injury
to distinguish characteristics of a two-degree-of-freedom joint from those of a one-degree-of-freedom joint

Neumann DA (2002). Wrist. In Neumann DA: Kinesiology of the Musculoskeletal System: Foundations for Physical Rehabilitation. Philadelphia: Mosby. Chapter 7, pp. 172-193.
Smith LK, Weiss EL, Don Lehmkuhl L (eds, 1996). Brunnstrom's Clinical Kinesiology, 5th ed. Philadelphia, F.A. Davis. Chapter 6, pp. 180-222.
Barr AE et al. (2001). Biomechanics of the wrist and hand. In Nordin M & Frankel VH: Basic Biomechanics of the Musculoskeletal System. Philadelphia: Lippincott Williams & Wilkins. Chapter 14, pp.358-387.

Functions of the Wrist

To argument fine hand and finger function

To control length/ tension of finger long flexors and extensors

To provide stability for skilled or forceful hand movements

Joint Structure of the Wrist

Joints at the wrist

radiocarpal joint： primary joint for wrist extension

midcarpal joint： primary joint for wrist flexion

intercarpal joints

distal radioulnar joint： forearm pronation/ supination

Carpal bones

proximal row scaphoid lunate triquetrum pisiform distal row trapezoid trpezium capitate hamate
NO muscles insert into the proximal carpal row.

Radiocarpal joint

proximal component： biconcave distal end of the radius and articular disc

the carpal bones only articulate with the radius

distal component： biconvex proximal row of the carpal bones (scaphoid, lunate, and triquetrum)

joint type： convex on concave

motions：

wrist flexion/ extension with dorsal/ palmar glide of the proximal row of the carpal bones on the distal radius

wrist radial/ ulnar deviation with ulnar/ radial glide of the proximal row of the carpal bones on the distal radius

DOF = 2

rest position： slight wrist extension (10º)

closed packed position： full wrist extension

Midcarpal joint

trapezoid and trapezium on scaphoid

capitate scaphoid

capitate on lunate

capitate on triquetrum

hamate on triquetrum

Intercarpal joints

trapezoid on capitate

hamate on capitate

pisiform on triquetrum

Distal radioulnar joint

proximal component： convex ulnar head

distal component： concave ulnar notch of the radius

NOTE: different synovial joint from the radiocarpal joint

joint type： pivot joint

motions：

forearm pronation with anterior glide of the radial head

forearm supination with posterior glide of the radial head

DOF = 1

Carpal tunnel

proximal transverse arch covered with flexor retinaculum

All extrinsic finger long flexors and median nerve passes through carpal tunnel except flexor digitorum ulnaris

carpal tunnel syndrome

increase intratunnel pressure

compression of median nerve

see Neumann Fig 7-5, Fig 7-6 on p.175 and Fig 7-21 on p.187

Anatomical snuff box

also named forvea radialis

area bounded by tendons of

extensor pollicis longus

extensor pollicis brevis

Kinematics of the Wrist

Wrist flexion and extension

joint involved wrist flexion radiocarpal joint: 40% midcarpal joint: 60% wrist extension radiocarpal joint: 67% midcarpal joint: 33% plane of motion： sagittal plane axis of rotation a frontal axis through the center of the capitate palpation： the area just proximal to the base of the third metacarpal bone

osteokinematic movements

range of motion (ROM)

0 ~ 85 /90º of wrist flexion

0 ~ 75/ 80º of wrist extension

functional range： from 10º of wrist flexion to 35º of wrist extension

NOTE： Loss of wrist function does not seriously impede performance of daily activities

closed kinematic chain motions

push-up (伏地挺身)

push against the wall

arthrokinematic movements (convex on concave)

radiocarpal joint

distraction of the proximal row of the carpal bones on the radius

dorsal glide (posterior glide) of the proximal row of the carpal bones on the radius with wrist flexion

volar glide (palmar glide or anterior glide) of the proximal row of the carpal bones on the radius with wrist extension

midcarpal joint

distraction of the distal row of the carpal bones on the proximal row

dorsal glide (posterior glide) of the distal row of the carpal bones on the proximal row with wrist flexion

volar glide (palmar glide or anterior glide) of the distal row of the carpal bones on the proxiaml row with wrist extension

Some intercarpal movements are also found during wrist motions.

factors limiting wrist flexion

dorsal radiocarpal ligaments： radiolunate, radiotriquetrol, radioscaphoid

factors limiting wrist extension

dorsal surface of the radius

palmar ligaments： stronger than the dorsal ligaments

Fix your wrist with any kind of bandages or tapes. Try to feel how inconvenient you would meet during daily activities.

Wrist radial/ ulnar deviation

joint involved

radial deviation (abduction)

most in midcarpal joint (15º)

radiocarpal joint

intercarpal joints

ulnar deviation (adduction)

most in radiocarpal joint (30º)

midcarpal joint

intercarpal joints

plane of motion： frontal plane

axis of rotation

a line perpendicular to the plane of the palm through the intersection of the capitate and lunate

palpation： the area just proximal to the base of the third metacarpal bone is the capitate

osteokinematic movements

range of motion (ROM)

0 ~ 15/ 25º of wrist radial deviation

0 ~ 35/ 45º of wrist ulnar deviation

closed kinematic chain motions

open or close a can

arthrokinematic movements (convex on concave)

radiocarpal joint

ulnar glide of the proximal row of the carpal bones on the radius with wrist radial deviation

radial glide of the proximal row of the carpal bones on the radius with wrist ulnar deviation

midcarpal joint

ulnar glide of the distal row of the carpal bones on the proximal row with wrist radial deviation

radial glide of the distal row of the carpal bones on the proximal row with wrist ulnar deviation

Some intercarpal movements are also found during wrist motions.

Factors checking radial deviation

radial styloid process

ulnar collateral ligament： from styloid process of the ulna to pisiform and troquetrum

Factors checking ulnar deviation

radial collateral ligament: from styloid process of the radius to scaphoid

Wrist circumduction

cone-like motion that us a combination of wrist flexion, extension, radial deviation, and ulnar deviation

wrist flexion à radial deviation à extension à ulnar deviation

wrist flexion à ulnar deviation à extension à radial deviation

Forearm pronation/ supination

joint involved

proximal radioulnar joint

distal radioulnar joint

humeroradial joint

plane of motion： transverse plane

axis of rotation

passing through the centers of both the radial and the ulnar heads

not parallel to the longitudinal axis of the forearm

osteokinematic movements

motions：

the radial head rotates on the ulna within the annular ligament
the radial head spins on the capitulum of the humerus
the ulnar notch of the radius rotates on the ulnar head

range of motion (ROM)

pronation： 0-70º

supination： 0-85º

Note: Pure motions occur as the elbow is held in the 90° of flexion. If the elbow is extended, shoulder rotation occurs simultaneously with forearm rotation.

functional range： 50º of pronation to 50º of supination

closed kinematic chain motions

open the door knob

open a can

arthrokinematic movements

proximal radioulnar joint (convex on concave)

anteromedial gliding of the radius on the ulna with forearm supination

posterolateral gliding of the radius on the ulna with forearm pronation

humeroradial joint (concave on convex)

spinning of the radius on the humerus with forearm supination/ pronation

distal radioulnar joint (concave on convex)

anterior gliding of the radius on the ulna with forearm pronation

posterior gliding of the radius on the ulna with forearm supination

Distal Radioulnar Joint

Muscles at the Wrist

Wrist flexors

palmar longus

flexor carpi radialis

flexor carpi ulnaris

flexor digitorum superficialis

Wrist extensors

extensor carpi radialis longus

extensor carpi radialis brevis

extensor carpi ulnaris

extensor digitorum communis

Muscles for wrist radial deviation

abductor pollicis longus

extensor pollicis longus and brevis

extensor carpi radialis longus and brevis

flexor carpi radialis

Muscles for wrist ulnar deviation

flexor carpi ulnaris

extensor carpi ulnaris

Forearm pronators

pronator teres

acts as forearm pronator

stabilizes proximal radioulnar joint

approximates humeroradial joint

pronator quadratus

activates during all pronation activities

Forearm supinators

biceps brachii

supinator

Wrist Stability

Factors Affecting Wrist Stability

bony configuration： most important

tension of ligaments

extrinsic and intrinsic ligaments

anterior and posterior radiocarpal ligaments

radial collateral ligament： prevents ulnar deviation stress

ulnar collateral ligament： prevents radial deviation stress

interosseous membrane

muscular arrangement

no muscle inserts on carpals excepts flexor carpi ulnaris

What if

fall down to the ground with wrist hyperextension?

Factors affecting the stability of the distal radioulnar joint

bony configuration

interosseous membrane

What is instability？

Mechanism of Injury at the Wrist

Direct stress

compression stress à Colles’ fracture (distal radius fracture) with/ without dorsal displacement

Repeated stresses

repeated wrist flexion/extension motion à chronic tenosynovitis of common flexor tendon à carpal tunnel syndrome

repeated radial/ulnar deviation motion à chronic tenosynovitis of extnesor pollicis brevis and/or abductor pollicis longus à deQuervain syndrome

Established on 10/18/2002 and Last Updated 12/16/2004