Previous                         Home                         Next

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

ObjectivesĄG After studying this topic, the students will be able to

  1. to identify the structure of the wrist, including joint type, articular shape, and the surrounding tissues
  2. to describe joint motions occurring at the wrist, including physiological and accessory movements, muscle actions, and factors checking wrist motions
  3. to understand the stability mechanism of the wrist and the possible mechanisms of injury
  4. to distinguish characteristics of a two-degree-of-freedom joint from those of a one-degree-of-freedom joint
  1. Neumann DA (2002).  Wrist.  In Neumann DA: Kinesiology of the Musculoskeletal System: Foundations for Physical Rehabilitation. Philadelphia: Mosby.  Chapter 7, pp. 172-193.
  2. Smith LK, Weiss EL, Don Lehmkuhl L (eds, 1996). Brunnstrom's Clinical Kinesiology, 5th ed.  Philadelphia, F.A. Davis.  Chapter 6, pp. 180-222.
  3. 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

Ą@

  • 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
  •   back to top


    Joint Structure of the Wrist

    Ą@

    Joints at the wrist

  • radiocarpal jointĄG primary joint for wrist extension
  • midcarpal jointĄG primary joint for wrist flexion
  • intercarpal joints
  • distal radioulnar jointĄG forearm pronation/ supination
  • Ą@

    Carpal bones

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

    Radiocarpal joint

  • proximal componentĄG biconcave distal end of the radius and articular disc
  • the carpal bones only articulate with the radius
  • distal componentĄG biconvex proximal row of the carpal bones (scaphoid, lunate, and triquetrum)
  • joint typeĄG convex on concave
  • motionsĄG
  • 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 positionĄG slight wrist extension (10º)
  • closed packed positionĄG full wrist extension
  • Ą@

    Midcarpal joint

  • trapezoid and trapezium on scaphoid
  • capitate scaphoid
  • capitate on lunate
  • capitate on triquetrum
  • hamate on triquetrum
  • Ą@

    Intercarpal joints

  • trapezoid on capitate
  • hamate on capitate
  • pisiform on triquetrum
  • Ą@

    Distal radioulnar joint

  • proximal componentĄG convex ulnar head
  • distal componentĄG concave ulnar notch of the radius
  • NOTE: different synovial joint from the radiocarpal joint
  • joint typeĄG pivot joint
  • motionsĄG
  • forearm pronation with anterior glide of the radial head
  • forearm supination with posterior glide of the radial head
  • DOF = 1
  • Ą@

    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
  • Ą@

    Anatomical snuff box

  • also named forvea radialis
  • area bounded by tendons of
  • extensor pollicis longus
  • extensor pollicis brevis
  •   back to top


    Kinematics of the Wrist

    Ą@

    Wrist flexion and extension

  • joint involved
  • wrist flexion
  • radiocarpal joint: 40%
  • midcarpal joint: 60%
  • wrist extension
  • radiocarpal joint: 67%
  • midcarpal joint: 33%
  • plane of motionĄG sagittal plane
  • axis of rotation
  • a frontal axis through the center of the capitate
  • palpationĄG 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 rangeĄG from 10º of wrist flexion to 35º of wrist extension
  • NOTEĄG Loss of wrist function does not seriously impede performance of daily activities
  • closed kinematic chain motions
  • push-up („ńŠaźŒš­)
  • 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 ligamentsĄG radiolunate, radiotriquetrol, radioscaphoid
  • factors limiting wrist extension
  • dorsal surface of the radius
  • palmar ligamentsĄG stronger than the dorsal ligaments
    1. 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 motionĄG frontal plane
  • axis of rotation
  • a line perpendicular to the plane of the palm through the intersection of the capitate and lunate
  • palpationĄG 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 ligamentĄG 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 motionĄG 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
  • motionsĄG
    1. the radial head rotates on the ulna within the annular ligament
    2. the radial head spins on the capitulum of the humerus
    3. the ulnar notch of the radius rotates on the ulnar head
  • range of motion (ROM)
  • pronationĄG 0-70º
  • supinationĄG 0-85º
  • Note: Pure motions occur as the elbow is held in the 90ąX of flexion.  If the elbow is extended, shoulder rotation occurs simultaneously with forearm rotation.
  • functional rangeĄG 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

      back to top


    Muscles at the Wrist

    Ą@

    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
  •   back to top


    Wrist Stability

    Ą@

    Factors Affecting Wrist Stability

  • bony configurationĄG most important
  • tension of ligaments
  • extrinsic and intrinsic ligaments
  • anterior and posterior radiocarpal ligaments
  • radial collateral ligamentĄG prevents ulnar deviation stress
  • ulnar collateral ligamentĄG 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 instabilityĄH
  •   back to top


    Mechanism of Injury at the Wrist

    Ą@

    Direct stress

  • compression stress à CollesĄŠ fracture (distal radius fracture) with/ without dorsal displacement
  • Ą@

    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
  •   back to top


    Established on 10/18/2002 and Last Updated 12/16/2004 © 2002 Huei-Ming Chai          All Right Reserved