Wrist and Hand

Question 1

Why is there more flexion in the wrist (85 deg) than extension (25 deg)?

Answer 1

because of the palmar tilt (10 deg posterior) at the end of the radius
- the carpal bones run into the radius quicker when they do extension vs. flexion

Question 2

Through what bone is the axis of rotation for the wrist?

Answer 2

capitate

Question 3

What are the top three fractured carpal bones?

Answer 3

1) scaphoid
2) lunate (1st most dislocated)
3) triquetrum

Question 4

Name the bones in order, looking from your palmar side and listing the bottom row then top row, radius to ulna.

Answer 4

bottom row: scaphoid, lunate, triquetrum, pisiform

top row: trapezium, trapezoid, capitate, hamate

Question 5

What’s the most moveable carpal bone?

Answer 5

lunate, making it the most dislocated bone

Question 6

Which side of the carpal bones is more moveable, medial or lateral?

Answer 6

medial is more moveable

Question 7

The motions at the wrist include what two joints?

Answer 7

1) radiocarpal (lunate moving on radius)

2) midcarpal (capitate moving on lunate)

Question 8

The radiocarpal joint has what basic arthrokinetic rule?

Answer 8

convex on concave

Question 9

What gives stability to the wrist?

Answer 9

collateral ligaments and intercarpal ligaments

Question 10

What carpal bone does Kienbock’s disease involve? What happens? How will the patient present?

Answer 10

• kienbock’s disease = avascular necrosis of the lunate, due to trauma or compression of bone
• patient presents with swelling, pain, and decreased ROM

Question 11

Where do most wrist fractures occur from breaking a fall?

Answer 11

at the waist of the scaphoid bone, since the styloid process of the radius runs right up into it

Question 12

How many degrees of ulnar and radial deviation can we get?

Answer 12

ulnar = 40 deg
radial = 20 deg

Question 13

What allows us to get more ulnar deviation than radial?

Answer 13

• b/c the radius directly articulates w/ carpal bones and the ulna doesn’t
• due to ulnar tilt of radius

Question 14

What are the degrees needed of ulnar/radial deviation to complete almost all ADLs?

Answer 14

30 degrees for ulnar deviation, 10 radial deviation

Question 15

How much flexion/extension do you need at the wrist to complete most ADLs?

Answer 15

40 degrees either way

Question 16

Describe the arthrokinematics of the radiocarpal joint for flexion/extension.

Answer 16

radiocarpal:

• flexion = palmar roll of lunate onto radius, dorsal slide
• extension = dorsal roll, palmar slide

Question 17

Describe the arthrokinematics of the midcarpal joint for flexion/extension.

Answer 17

midcarpal:

• flexion = palmar roll of capitate on lunate, dorsal slide
• extension = dorsal roll, palmar slide

Question 18

In flexion and extension, from which joint (midcarpal or radiocarpal) does most motion come from?

Answer 18

• split 50/50 for flex and extend

* for ulnar and radial deviation though, it’s 60% MIDCARPAL

Question 19

Describe the arthrokinetmatics of ulnar deviation.

Answer 19

1) lunate rolls ulnarly on radius, slides radially

2) capitate rolls ulnarly, slides radially

Question 20

At what position do we have the most grip strength?

Answer 20

30-35 degrees of wrist extension, 5 degrees ulnar deviation

Question 21

What happens to the lunate in volar intercalated segment instability (VISI)?

Answer 21

lunate displaced palmarly, angle to scaphoid is less than 30 (zig-zag deformity)

Question 22

T/F: The longer moment arm a muscle has, perpendicular to the axis of the muscle it’s acting on, the better it’s able to act on that muscle.

Answer 22

true

Question 23

T/F: The wrist extensors are stronger than the wrist flexors.

Answer 23

false, wrist flexors are stronger due to more CSA

Question 24

When the lunate creates an angle with the scaphoid that is greater than 60 deg, what kind of carpal instability has occurred?

Answer 24

dorsal intercalated segment instability (DISI)

Question 25

T/F: During wrist flexion, you have passive insufficiency of the wrist extensors.

Answer 25

true; too stretched to give full ROM

Question 26

T/F: During wrist flexion, you have active insufficiency of the wrist flexors.

Answer 26

true; too shortened to produce full flexion force

Question 27

What two muscles synergistically flex the wrist, allowing straight wrist flexion with no deviation?

Answer 27

flexor carpi ulnaris and radialis

Question 28

T/F: You have more ulnar deviators than radial deviators.

Answer 28

false, more radial: they do 15% greater isometric torque than ulnar deviators

Question 29

Which digits are more rigid?

Answer 29

2-3 are rigid, 4-5 give a lot of movement (as well as the thumb)

Question 30

What bones are moving on each other at the thumb joint?

Answer 30

metacarpal moves on the trapezium in the saddle joint

Question 31

Do the longitudinal/transverse diameters of the thumb follow the same longitudinal/transverse diameters of the SC, arthrokinematic wise?

Answer 31

yes: longitudinal goes in opposite ways, transverse goes in same way

Question 32

Adduction and abduction of the thumb moves in what diameter?

Answer 32

ad/ab = longitudinal diameter, so convex on concave

Question 33

Flexion and extension of the thumb occur in what diameter?

Answer 33

flex/extend = transverse diameter, so concave on convex

Question 34

Describe the arthrokinematics in the flexion/extension of the thumb.

Answer 34

``` flex = concave metacarpal rolls ulnarly, slides ulnarly extend = rolls radially, slides radially ```

Question 35

Do you get more motion in digit abduction when the fingers are flexed or extended?

Answer 35

fingers extended gives you more motion to do ad/abduction

Question 36

On what axis does wrist ulnar and radial deviation occur?

Answer 36

about the AP axis

Question 37

T/F: Extensor carpi ulnaris is better at extension than ulnar deviation.

Answer 37

false: ECU is best at ulnar deviation due to a longer moment arm to the ML axis

Question 38

T/F: The wrist flexors have 2x the CSA of the extensors.

Answer 38

true

Question 39

What muscle produces the greatest flexor torque of the three main wrist flexors?

Answer 39

FCU

Question 40

What is the purpose of having pulleys in the hands?

Answer 40

to hold down the tendons; although these can get thick and cause pain in digits during motion

Question 41

Which pulley is the most important? Why?

Answer 41

A1 @ MCP; it's thicker and more fibrous, so tendon can push its way through the pulley and cause trigger finger

Question 42

What is the normal range of motion at the IP joints?

Answer 42

70 deg flexion, 30 deg extension

Question 43

What are the arthrokinematics for all MCP joints in the hand, including IP on MCP?

Answer 43

proximal phalange moves on metacarpal, motion is in same directions since they're all concave on convex

Question 44

Can the MCP of the thumb do ab and adduction, like the MCP of the fingers?

Answer 44

no, thumb just does flexion/extension

Question 45

What is the position of function for the hand?

Answer 45

think of the splint picture: prevent contractures by keeping hand in slight extension; UD; MCP, DIP, PIP flexion; thumb abduction

Question 46

What's the difference between extrinsic and intrinsic plus positions?

Answer 46

1) extrinsic plus: use superficialis and profundus, and extensor digitorum, to get bear claw hand 2) intrinsic plus: use lumbricals and interossei to get lumbrical action

Question 47

What muscle offsets extensor digitorum while it extends the IPs so that hyperextension at the wrist doesn't occur?

Answer 47

flexor carpi radialis

Question 48

For a low-level fist, what muscle is activated first?

Answer 48

first, profundus, then superficialis

Question 49

What osteokinematics need to happen during power grip?

Answer 49

- flexed fingers (esp. 4 and 5) - adducted and flexed thumb - DAB interossei - slight WE and UD

Question 50

Compare boutonniere deformity and swan neck deformity.

Answer 50

boutonniere = flexed PIP, extended DIP | swan neck = extended PIP, flexed DIP

Question 51

Why does ulnar drift occur?

Answer 51

thumb adducts and the interossei can't resist that motion (the connective tissue they attach to is broken down), so those fingers begin to move ulnarly like the thumb

Question 52

Abductor pollicis brevis is used in what grip?

Answer 52

precision grip, to abduct thumb

Question 53

What does "power key" or "power pinch" involve?

Answer 53

DAB to abduct 1st digit toward thumb, adductor pollicis to bring thumb to lateral border of first digit

Question 54

What causes boutonniere deformity?

Answer 54

central tendon on dorsum of digit tears