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The Wrist and Finger Joints
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"Remember,"
  • Remember, a joint is simply two bones which articulate.  The wrist/hand region consists of 29 bones and multiple joints - which lends to high mobility.


  • Our goal is to understand functional anatomy in order to apply knowledge to physical therapy, exercise prescription, for example. (so we’ll stick to gross movements of the wrist/hand)
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Terminology
  • Wrist:
    • as a joint, it is the articulation between the forearm and hand.
    • Sometimes, the wrist is discussed as a region, which would include the carpal bones.
  • Hand
    • the bones distal to the wrist joint.
    • As a region, the wrist is part of the hand.
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Bones
  • 29 bones including:
    • (2 from the forearm, 27 from the hand)
    • distal aspect of the radius and ulna
    • 8 carpal (bulk of the hand)
    • 14 phalanges (the fingers)
    • 5 metacarpals
    • total: 2+8+14+5=29
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Bones
  • Radius and Ulna
    • the radius is more massive distally than the ulna
    • the ulna is more massive proximally than the radius
    • Remember, forearm pronation and supination are the result of the radius rotating about the ulna
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Bones
  • Carpal Bones
    • 8 total
    • 2 rows of 4
    • Proximal row:
      • pisiform, triquetrum, lunate, scaphoid
    • Distal row:
      • hamate, capitate, trapezoid, trapezium
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Bones
  • Metacarpals
    • 5
  • Phalanges
    • 3 per finger
    • 2 per thumb
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Joints
  • Wrist Joint
    • Classified as a Condyloid Joint
      • allows for flexion, extension, radial and ulnar deviation
      • Remember, radius=thumb side
    • The motion of the wrist is due to the articulation of the radius and proximal carpal bones (or Radiocarpal joint).
    • There is an articular disk between the distal aspect of the ulna and triquetrum
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Joints
  • Proximal and distal interphalangeal joints
    • Fingers:
      • classified as ginglymus joints
      • allows for flexion and extension
    • Thumb:
      • consists of three joints, the first two are classified as ginglymus joints
        • metacarpophalangeal: g.j.
        • interphalangeal: g.j.
        • carpometacarpal: trapezium and metacarpal; saddle jt.

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Movements of the wrist and hand
  • Wrist (remember start from anatomical position)
    • Flexion
      • (or palmer flexion): anterior deviation from anatomical position.
    • Extension: dorsal flexion
    • Abduction
      • (or radial deviation or radial flexion)
    • Adduction
      • (or ulnar deviation or ulnar flexion)
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Movements
  • Fingers
    • Flexion: anteriorly directed movement
    • Extension
    • Abduction: movement of the fingers away from the midline of the hand.
    • Adduction
    • Thumb opposition: movement of the thumb to oppose any of the phalanges
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Summary of bones and joints
  • 29 bones make up the wrist and hand
    • radius, ulna, carpals, metacarpals, phalanges
  • The wrist is primarily the articulation of the radius and proximal carpal bones
  • There are many joints in the wrist/hand
    • fingers: metacarpal phalangeal, proximal & distal interphalangeal
    • thumb: carpometacarpal, metacarpal ph., interphalangeal joints
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Summary of movements
  • Wrist:
    • flexion, extension, abduction, adduction
  • Fingers
    • flexion, extension
  • Thumb
    • Abduction, adduction, flexion, extension, opposition
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Muscles of the Wrist and Fingers
  • There are 15 critical muscles
    • 6 muscles are group as primary movers for wrist flexion and extension actions
    • 9 muscles are group as primary movers for hand (finger)
    • of the 15 muscles
      • 6 are primary movers for wrist ulnar deviation
      • 2 are primary movers for wrist radial deviation
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Muscles causing wrist actions
  • Wrist flexors
    • flexor carpi radialis
    • flexor carpi ulnaris
    • palmaris longus
  • Wrist extensors
    • extensor carpi radialis longus
    • extensor carpi radialis brevis
    • extensor carpi ulnaris
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Muscles
  • Finger flexors
    • flexor digitorum superficialis
    • flexor digitorum profundus
  • Thumb flexor
    • flexor pollicis longus
  • Finger extensors
    • extensor digitorum
    • extensor indicis
    • extensor digiti minimi
  • Thumb extensor
    • extensor pollicis longus
    • extensor pollicis brevis
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Muscles
  • Wrist radial flexors
    • flexor carpi radialis
    • extensor carpi radialis longus
    • extensor carpi radialis brevis
    • abductor pollicis longus
    • extensor pollicis longus
    • extensor pollicis brevis
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Muscles
  • Wrist ulnar flexors
    • flexor carpi ulnaris
    • extensor carpi ulnaris
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"Wrist flexors"
  • Wrist flexors
    • Origins generally on the anteromedial aspect of the proximal aspect of the forearm and medial epicondyle
    • Insertions: anterior aspect of the wrist and hand
  • Wrist extensors
    • origins: posterolateral aspect of the proximal forearm & lateral humeral epicondyle
    • insertions: posterior aspect of wrist and hand
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"Wrist abductors"
  • Wrist abductors
    • Origin: anterior or posterior aspect of forearm
    • Insertion: radial side of hand
  • Wrist adductors
    • Origin: ant or post aspect of forearm
    • Insertion: ulnar side of hand
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Abductor pollicis longus (p155)
  • Origin
    • posterior aspect of radius and ulnar midshaft
  • Insertion
    • Base of 1st metacarpal (thumb)
  • Action
    • thumb abduction
    • radial flexion
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Extensor indicis (p156)
  • Origin
    • middle to distal one-third of posterior ulna
  • Insertion
    • base of middle and distal phalanxes
  • Action
    • extension of index finger (1st)
    • weak wrist extensor
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Extensor pollicis brevis (p157)
  • Origin
    • posterior surface of lower middle radius
  • Insertion
    • base of proximal phalanx of thumb
  • Action
    • thumb extensor
    • weak wrist extensor
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Extensor pollicis longus (p158)
  • Origin
    • posterior lateral surface of middle aspect of ulna
  • Insertion
    • Base of distal phalanx of thumb (dorsal surface)
  • Action
    • wrist extension
    • thumb extension
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Flexor digitorum profundus (p159)
  • Origin
    • proximal three-fourths of the anterior and medial ulna
  • Insertion
    • Base of the distal phalanxes
  • Action
    • flexion of four fingers
    • wrist flexion
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Flexor pollicis longus (p160)
  • Origin
    • middle anterior surface of radius and anterior medial border of ulna
  • Insertion
    • base of distal phalanx of thumb
  • Action
    • thumb flexion
    • wrist flexion
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Extensor carpi radialis brevis (p161)
  • Origin
    • lateral epicondyle of humerus
  • Insertion
    • Base of 3rd metacarpal (dorsal surface)
  • Action
    • wrist extensor
    • Radial flexion
    • weak elbow flexor
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Extensor carpi radialis longus (p162)
  • Origin
    • humerus, lower 3rd of lateral supracondylar ridge and lateral epicondyle of humerus
  • Insertion
    • Base of 2nd metacarpal (dorsal surface)
  • Action
    • wrist extensor
    • radial flexion
    • weak elbow extensor
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Extensor carpi ulnaris (p163)
  • Origin
    • lateral epicondyle of humerus
  • Insertion
    • Base of 5th metacarpal
  • Action
    • Wrist extension
    • Ulnar flexion
    • weak elbow extensor
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Extensor digiti minimi (p164)
  • Origin
    • lateral epicondyle of the humerus
  • Insertion
    • base of middle and distal phalanxes of 5th finger (i.e. pinky)
  • Action
    • ‘pinky’ extension
    • weak wrist extensor
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Extensor digitorum (p165)
  • Origin
    • Lateral epicondyle of humerus
  • Insertion
    • bases of middle and distal phalanges of fingers
  • Action
    • finger extension
    • wrist extension
    • weak elbow extensor
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Flexor carpi radialis (p166)
  • Origin: medial epicondyle of humerus
  • Insertion: base of 2nd & 3rd metacarpals, anterior surface
  • Action:
    • wrist flexion
    • radial flexion
    • weak elbow flexor
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Flexor digitorum superficialis (p168)
  • Origin
    • medial epicondyle of humerus
    • ulnar head: medial coronoid process
    • Radial head: upper two-thirds of anterior border of radius
  • Insertion
    • lateral and medial sides of middle 3 phalanges (palmer surface)
  • Action
    • finger flexion
    • wrist flexion
    • weak elbow flexor
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Palmaris longus (p169)
  • Origin
    • medial epicondyle of humerus
  • Insertion
    • palmar aponeurosis
  • Action
    • wrist flexion
    • weak elbow flexor
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Flexor carpi ulnaris
  • Origin
    • medial epicondyle of humerus
  • Insertion
    • pisiform, hamate & base of 5th metacarpal
  • Action
    • wrist flexion
    • ulnar flexion
    • weak flexor of elbow