Wrist (Part II)

Question 1

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

Answer 1

Two

• Flexion/extension
• Ulnar/radial deviation

*NOT circumduction (combination of the above movements)

Question 2

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

Answer 2

greater

greater

Question 3

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

Answer 3

radial

ulnar

Question 4

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

Answer 4

oblique (dart thrower)

Question 5

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

Answer 5

capitate

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

Question 6

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

Answer 6

in nearly a medial-lateral line

Question 7

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

Answer 7

in nearly an anterior-posterior line

Question 8

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

Answer 8

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

Question 9

What limits end-range extension?

Answer 9

• Stiffness in thick palmar radiocarpal ligaments

- Large palmar tilt of distal radius may limit extension range

Question 10

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

Answer 10

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

Question 11

Why does ulnar deviation normally double radial deviation?

Answer 11

Because of the ulnar tilt of the distal radius

Question 12

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

Answer 12

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

Question 13

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

Answer 13

Movement occurs simultaneously at both radiocarpal and midcarpal joints

Question 14

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

Answer 14

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

Question 15

3 articulations of the central column of the wrist

Answer 15

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

Question 16

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

Answer 16

concave

convex

Question 17

Describe the arthrokinematics at the radiocarpal joint during extension

Answer 17

The convex surface of the lunate rolls dorsally and slides palmarly

Question 18

Describe the arthrokinematics at the radiocarpal joint during flexion

Answer 18

The convex surface of the lunate rolls palmarly and slides dorsally

Question 19

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

Answer 19

concave

convex

Question 20

Describe the arthrokinematics at the midcarpal joint during extension

Answer 20

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

Question 21

Describe the arthrokinematics at the midcarpal joint during flexion

Answer 21

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

Question 22

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

Answer 22

They must work as a unit

Question 23

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

Answer 23

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

Question 24

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

Answer 24

midcarpal joint and radiocarpal joint

Question 25

Describe the arthrokinematics at the radiocarpal joint during ulnar deviation

Answer 25

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

Question 26

Describe the arthrokinematics at the midcarpal joint during ulnar deviation

Answer 26

The capitate rolls ulnarly and slides radially slightly

Question 27

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

Answer 27

the articular disc

Question 28

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

Answer 28

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

Question 29

Describe the arthrokinematics at the radiocarpal joint during radial deviation

Answer 29

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

Question 30

Describe the arthrokinematics at the midcarpal joint during radial deviation

Answer 30

The capitate rolls radially and slides ulnarly slightly

Question 31

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

Answer 31

The carpus impinges against the styloid process of the radius

Question 32

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

Answer 32

midcarpal joint

Question 33

2 Common Forms of Carpal Instability

Answer 33

- Rotational collapse of wrist | - Ulnar translocation of carpus

Question 34

A rotational collapse of the wrist is aka what?

Answer 34

"zigzag” deformity

Question 35

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

Answer 35

- Dorsal intercalated segment instability | - Volar intercalated segment instability

Question 36

What occurs during dorsal intercalated segment instability (DISI)?

Answer 36

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

Question 37

What occurs during volar intercalated segment instability (VISI)?

Answer 37

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

Question 38

Which ligament is typically damaged with a VISI?

Answer 38

lunotriquetral ligament

Question 39

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

Answer 39

25°

Question 40

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

Answer 40

42

Question 41

Describe the “Double-V” System of wrist ligaments

Answer 41

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

Question 42

The distal inverted V is formed by what 2 ligaments?

Answer 42

medial and lateral legs of palmar intercarpal ligament

Question 43

The proximal inverted V is formed by what 2 ligaments?

Answer 43

the lunate attachments of palmar ulnocarpal and palmar radiocarpal ligaments

Question 44

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

Answer 44

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

Question 45

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

Answer 45

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

Question 46

What are the 3 primary wrist extensor muscles?

Answer 46

- Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor carpi ulnaris

Question 47

What are the 4 secondary wrist extensor muscles?

Answer 47

- Extensor digitorum - Extensor indicis - Extensor digiti minimi - Extensor pollicis longus

Question 48

What role do wrist extensor muscles play in grip?

Answer 48

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

Question 49

Maximal grip force occurs at about __° of extension

Answer 49

30°

Question 50

What are the 3 primary wrist flexor muscles?

Answer 50

- Flexor carpi radialis - Flexor carpi ulnaris - Palmaris longus

Question 51

What are the 5 secondary wrist flexor muscles?

Answer 51

- Flexor digitorum profundus - Flexor digitorum superficialis - Flexor pollicis longus - Abductor pollicis longus - Extensor pollicis brevis

Question 52

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

Answer 52

40° of flexion

Question 53

What are the 7 radial deviators of the wrist?

Answer 53

- Extensor carpi radialis longus - Extensor carpi radialis brevis - Extensor pollicis longus - Extensor pollicis brevis - Flexor carpi radialis - Abductor pollicis longus - Flexor pollicis longus

Question 54

What are the 4 ulnar deviators of the wrist?

Answer 54

- Extensor carpi ulnaris - Flexor carpi ulnaris - Flexor digitorum profundus and superficialis - Extensor digitorum

Question 55

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

Answer 55

the capitate