wrist and hand extras

Question 1

key points

Answer 1

• Alignment of distal radius & ulna affects the stability of carpals & wrist
• Stable column of the hand
• Path of force transfer hand to forearm through the scaphoid
• MCP collateral ligaments are taut in flexed position
• Functional combinations of wrist movements requires coordination of many muscles
• Contraction of a muscle that crosses the wrist results in a joint reaction force
• Hand activities require interaction of extrinsic and intrinsic muscles

Question 2

wrist joints

Answer 2

rely heavily on ligaments for stability

• The 1st CMC jt is the most mobile; the 1st MCP AND IP are the least mobile

Question 3

carpals rows

Answer 3

The distal row of carpals move as a unit – use capitate as a reference
• The carpals in the proximal row move more independently
- The importance of lunate in proximal carpal row stability

Question 4

articular surfaces

Answer 4

• Convex – concave articular surfaces exhibit more movement than flat or irregular
Interlocking surfaces = stability
Flat = gliding; minimal movement

Question 5

8 carpal bones

Answer 5

Scaphoid, Lunate, Triquestrum, Pisiform, Trapezium, Triquetrum, Capitate, Hammate

Question 6

Extensor hoods:

Answer 6

• Extensor digitorum tendon
• Extensor pollicis longus tendon
• Lumbricales & interossei
- Lateral bands reconverge & insert into distal phalanx
- Central tendon inserts into base of middle phalanx
 Lumbricale action:
• MCP FLEXION
• IP EXTENSION

Question 7

Distal Ulna

Answer 7

fovea – attaches to apex of fibrocartilage disc

articular circumference - articulates with upper surface of triangular articular disc

Question 8

dorsal tubercle of radius

Answer 8

is a pulley to redirect the pull of extensor pollicus longus

the scapholunate joint line is aligned just distal to the dorsal tubercle

Question 9

scaphoid

Answer 9

tubercle for attachment of the transverse carpal ligament
the articular surface for the radius is convex
the articular surface for the capitate is concave
the remaining articular surfaces are flat = less movement
proximal and distal poles separated by the waist

Question 10

lunate

Answer 10

convex proximally to articulate with the radius and the scaphoid (radiocarpal joint)
The volar surface is narrower than the dorsal surface. Together with the volar inclination of the distal radius may help explain why the lunate tends to sublux / dislocate in a inferior direction.

Question 11

trapezium

Answer 11

tubercle for attachment of the transverse carpal lig.

Question 12

hamate

Answer 12

hamulus / hook which provides attachment for 4th and final transverse carpal ligament

Question 13

scaphoid fractures

Answer 13

most common
The common mechanism of injury is forceful hyperextension where the dorsal border of the distal radius impacts the wrist
if impact > 95˚ hyperextension = scaphoid fractues
if impact < 95˚ hyperextension = distal radial fractues

Question 14

avascular necrosis

Answer 14

Loss of blood to the bone
- nutrient foramina located in distal pole of scaphoid which leaves proximal frag. without blood supply > delays union of fracture and effects wrist joint

Question 15

dupytren’s contracture

Answer 15

progressive flx of ulnar fingers (4th and 5th finger)

- thickening and shortening of palmar fascia, resulting in clawed fingers as they’re pulled towards hands.

Question 16

trigger finger

Answer 16

influenced by rheumatoid arthritis
tendon sheath susceptible to inflammation > swelling compressed tendon and compromises vascular flow
- as a result, fingers get stuck in flx
- thickening of synovial sheeth

Question 17

Which muscles travel through the carpal tunnel?

Answer 17

FDS (4 tendons), FDP (4 tendons), FPL

Question 18

Describe the arrangement of the flexor tendons in their tendon sheaths.

Answer 18

4 and 5 share a sheeth for tendons whilst 1-3 have own

Question 19

What is the general role of extrinsic muscles of the hand?

Answer 19

support structures

Question 20

boundaries of snuffbox

Answer 20

Radial side - extensor pollicus brevis & abductor pollicus longus
Ulnar side - extensor pollicus longus
radial artery travels through snuffbox

Question 21

De Quervain’s tenosynovitis

Answer 21

thickening and narrowing of the connective tissue compartment containing the abductor pollicus longus and extensor pollicus brevis.
hurts to move, loss of mobility and control