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625: Biomechanics & Kinesiology > Wrist (Part II) > Flashcards

Wrist (Part II) Flashcards

1
Q

How many degrees of freedom does the wrist have? What are they?

A

Two

  • Flexion/extension
  • Ulnar/radial deviation

*NOT circumduction (combination of the above movements)

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2
Q

Flexion is ____ than extension and ulnar deviation is ___ than radial deviation

A

greater

greater

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3
Q

Extension tends to occur with ____ deviation whereas flexion tends to occur with ____ deviation.

A

radial

ulnar

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4
Q

The natural path of motion for the wrist follows what type of path?

A

oblique (dart thrower)

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5
Q

Axis of rotation for wrist movements passes through head of what bone? Why?

A

capitate

The firm articulation between the capitate and base of 3rd metacarpal bone causes rotation of capitate to direct osteokinematic path of entire hand

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6
Q

During flexion and extension where does the axis of rotation run?

A

in nearly a medial-lateral line

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7
Q

During radial and ulnar deviation where does the axis of rotation run?

A

in nearly an anterior-posterior line

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8
Q

The wrist rotates in sagittal plane about ___°-___°. How much is attributed to flexion and how to extension?

A

130°-160°
Flexion = 70° - 85°
Extension = 60° - 75°

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9
Q

What limits end-range extension?

A
  • Stiffness in thick palmar radiocarpal ligaments

- Large palmar tilt of distal radius may limit extension range

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10
Q

The wrist rotates in frontal plane about ___°-___°. How much is attributed to radial deviation and how to ulnar deviation?

A

50° - 60°
Ulnar Deviation = 35° - 40°
Radial Deviation = 15° - 20°

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11
Q

Why does ulnar deviation normally double radial deviation?

A

Because of the ulnar tilt of the distal radius

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12
Q

What is the “average” position of function for the wrist?

A

About 10°-15° of extension and 10° of ulnar deviation

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13
Q

Carpal kinematics are typically described as a double-joint system, why?

A

Movement occurs simultaneously at both radiocarpal and midcarpal joints

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14
Q

What does the “central column” of the wrist consist of?

A

The distal radius, lunate, capitate, and 3rd metacarpal

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15
Q

3 articulations of the central column of the wrist

A

Radiocarpal (between radius and lunate)
Midcarpal (between lunate and capitate)
Carpometacarpal (between capitate and 3rd metacarpal)

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16
Q

The distal end of the radius is con__ and the proximal surface of the lunate is con___.

A

concave

convex

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17
Q

Describe the arthrokinematics at the radiocarpal joint during extension

A

The convex surface of the lunate rolls dorsally and slides palmarly

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18
Q

Describe the arthrokinematics at the radiocarpal joint during flexion

A

The convex surface of the lunate rolls palmarly and slides dorsally

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19
Q

The distal surface of the lunate is con__ and the proximal surface of the capitate is con___.

A

concave

convex

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20
Q

Describe the arthrokinematics at the midcarpal joint during extension

A

The head of capitate rolls dorsally on lunate and slides in palmar direction

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21
Q

Describe the arthrokinematics at the midcarpal joint during flexion

A

The head of capitate rolls palmarly on lunate and slides in dorsal direction

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22
Q

In order for full wrist extension and flexion to occur what must happen at the radiocarpal and midcarpal joints?

A

They must work as a unit

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23
Q

What is the close-packed position for the wrist and why?

A

Full extension because it elongates palmar radiocarpal ligaments and all muscles that cross on palmar side of wrist which help to stabilize it

24
Q

Which joints attribute to most of the movement during ulnar deviation?

A

midcarpal joint and radiocarpal joint

25
Q

Describe the arthrokinematics at the radiocarpal joint during ulnar deviation

A

The scaphoid, lunate, and triquetrum roll ulnarly and slide radially majorly

26
Q

Describe the arthrokinematics at the midcarpal joint during ulnar deviation

A

The capitate rolls ulnarly and slides radially slightly

27
Q

During full range of ulnar deviation what does the triquetrum come into contact with?

A

the articular disc

28
Q

Describe the mechanism that occurs to stabilize the wrist for activities that require large gripping forces

A

The hamate compresses against the triquetrum which pushes the proximal row of carpal bones against the styloid process of the radius

29
Q

Describe the arthrokinematics at the radiocarpal joint during radial deviation

A

The scaphoid, lunate, and triquetrum roll radially and slide ulnarly

30
Q

Describe the arthrokinematics at the midcarpal joint during radial deviation

A

The capitate rolls radially and slides ulnarly slightly

31
Q

What limits the amount of radial deviation at the radiocarpal joint?

A

The carpus impinges against the styloid process of the radius

32
Q

Does more radial deviation occur at the radiocarpal or midcarpal joint?

A

midcarpal joint

33
Q

2 Common Forms of Carpal Instability

A
  • Rotational collapse of wrist

- Ulnar translocation of carpus

34
Q

A rotational collapse of the wrist is aka what?

A

“zigzag” deformity

35
Q

There are 2 types of zigzag deformities: DISI and VISI. What do each stand for?

A
  • Dorsal intercalated segment instability

- Volar intercalated segment instability

36
Q

What occurs during dorsal intercalated segment instability (DISI)?

A

During a fall onto an outstretched hand the lunate dislocates so its distal articular surface faces dorsally

37
Q

What occurs during volar intercalated segment instability (VISI)?

A

Dislocation of the lunate so that its distal articular surface faces volarly (palmarly)

38
Q

Which ligament is typically damaged with a VISI?

A

lunotriquetral ligament

39
Q

The distal end of the radius angles towards the ulnar at an angle of about __°. This

A

25°

40
Q

A wrist with an ulnar tilt of 25° has an ulnar translation force of __% of total compression force that crosses wrist

A

42

41
Q

Describe the “Double-V” System of wrist ligaments

A

In a neutral position, four ligaments appear as two inverted Vs

42
Q

The distal inverted V is formed by what 2 ligaments?

A

medial and lateral legs of palmar intercarpal ligament

43
Q

The proximal inverted V is formed by what 2 ligaments?

A

the lunate attachments of palmar ulnocarpal and palmar radiocarpal ligaments

44
Q

During ulnar deviation what ligaments of the “double-V” system are stretched?

A

The lateral leg of the palmar intercarpal ligament and fibers of the palmar ulnocarpal ligament

45
Q

During radial deviation what ligaments of the “double-V” system are stretched?

A

The medial leg of the palmar intercarpal ligament and fibers of the palmar radiocarpal ligament

46
Q

What are the 3 primary wrist extensor muscles?

A
  • Extensor carpi radialis longus
  • Extensor carpi radialis brevis
  • Extensor carpi ulnaris
47
Q

What are the 4 secondary wrist extensor muscles?

A
  • Extensor digitorum
  • Extensor indicis
  • Extensor digiti minimi
  • Extensor pollicis longus
48
Q

What role do wrist extensor muscles play in grip?

A

They maintain optimal length of finger flexors and block wrist flexion tendency caused by activated finger flexor muscles

49
Q

Maximal grip force occurs at about __° of extension

A

30°

50
Q

What are the 3 primary wrist flexor muscles?

A
  • Flexor carpi radialis
  • Flexor carpi ulnaris
  • Palmaris longus
51
Q

What are the 5 secondary wrist flexor muscles?

A
  • Flexor digitorum profundus
  • Flexor digitorum superficialis
  • Flexor pollicis longus
  • Abductor pollicis longus
  • Extensor pollicis brevis
52
Q

What is the joint angle of peak torque for wrist flexion?

A

40° of flexion

53
Q

What are the 7 radial deviators of the wrist?

A
  • Extensor carpi radialis longus
  • Extensor carpi radialis brevis
  • Extensor pollicis longus
  • Extensor pollicis brevis
  • Flexor carpi radialis
  • Abductor pollicis longus
  • Flexor pollicis longus
54
Q

What are the 4 ulnar deviators of the wrist?

A
  • Extensor carpi ulnaris
  • Flexor carpi ulnaris
  • Flexor digitorum profundus and superficialis
  • Extensor digitorum
55
Q

What carpal bone is the axis of rotation for radial and ulnar deviation?

A

the capitate

625: Biomechanics & Kinesiology (15 decks)

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