L4: Bones, ligaments and joints of the hand (incl. wrist)

Question 1

bones of the hand

Answer 1

carpals (8)
- 2 rows of 4
metacarpals (5)
- 1st [thumb] to 5th [wee finger]
phalanges (14)
- proximal
- middle *
- distal

Question 2

carpals

Answer 2

scaphoid
lunate
triquetrum
pisiform
trapezium
trapezoid
capitate
hamate

Question 3

carpal tunnel

Answer 3

the carpal tunnel is formed by:
carpals: floor, medial and lateral wall
transverse carpal ligament: roof

transverse carpal ligament is aka flexor retiaculum

medial nerve enters hand from forearm by passing through the carpal tunnel

Question 4

carpal tunnel syndrome

Answer 4

Carpal tunnel syndrome caused by compression of median nerve
Compression of median nerve usually occurs due to increased pressure in carpal tunnel

Causes:
*Injury (swelling)
*Tendon hypertrophy

Question 5

metacarpals

Answer 5

5 in total
features: base, shaft, head
base articulates with carpals
head articulates with phalanges
thumb = 1, little finger = 5

Question 6

boxers fracture

Answer 6

inexperienced boxers tend to hook punch

4th and 5th metacarpals are weaker than other and less well supported
they are easily fractures during hoot punches

Question 7

phalanges

Answer 7

proximal, middle*, distal
* thumb has no middle phalanx
features:
proximal + middle phalanx: base, shaft, head
distal phalanx: base, shaft, tubercle

Question 8

mallet finger

Answer 8

extensor tendon rupture or avulsion injury leaves distal phalanx in the flexed position

Question 9

jersey finger

Answer 9

finger caught in jersey
due to momentum of players finger is hyperextended and the flexor tendon is torn
may also avulse a piece of bone
patient no longer able to flex finger
affected finger resides in affected position

Question 10

wrist joint

Answer 10

complex, involves many joints:
- distal radioulnar joint
- radiocarpal joints
- intercarpal joints

Question 11

distal radioulnar joint

Answer 11

ulnar head in ulnar notch of radius
synovial pivot joint
allows for supination and pronation of forearm

Question 12

radiocarpal joint

Answer 12

joint between:
- distal radius/ulnar fibrocartilaginous disc
- proximal row of carpals; scaphoid, lunate, triquetrum

synovial condyloid joint
- on one side, joint capsule attached to distal radius and ulna
- on other side, joint capsule is attached to proximal carpals

Question 13

radiocarpal joint movements

Answer 13

flexion / extension
radial deviation [abduction] / ulnar deviation[adduction]
circumduction

Question 14

intercarpal joints

Answer 14

augment range of wrist movements

plane synovial joints
between carpals of a given row e.g. scaphoid and lunate |||

Question 15

midcarpal joints

Answer 15

between proximal and distal row of carpals
synovial condyloid joints

Question 16

wrist joint capsule

Answer 16

joint space is mostly continuous between wrist and hand
synovial membrane lines capsule
capsule reinforced by ligaments:
- anterior interosseous ligaments
- posterior interosseous ligaments

Question 17

wrist joint: strengthened by 6 ligaments

Answer 17

radial collateral ligament
ulnar collateral ligament
palmar ulnocarpal ligament
palmar radiocarpal ligament
dorsal ulnocarpal ligament
dorsal radiocarpal ligament

Question 18

radial collateral ligament

Answer 18

radial styloid to tubercle of scaphoid

Question 19

ulnar collateral ligament

Answer 19

ulnar styloid to triquetrum

Question 20

palmar ulnocarpal ligament

Answer 20

strengthens capsule

Question 21

palmar radiocarpal ligament

Answer 21

radius to both rows of carpal bones
fibres directed such that hand follows radius during supination of forearm

Question 22

dorsal ulnocarpal ligament

Answer 22

ulna to triquetrum

Question 23

dorsal radiocarpal ligament

Answer 23

radius to both rows of carpals
fibres directed such that hand follows radius during pronation

Question 24

colle’s fracture

Answer 24

typically due to FOOSH
fracture of radius (and sometimes ulna) approx. 2.5cm from distal end
distal radial fragment moves posteriorly and proximally
there is also dislocation of the radioulnar joint distally
dorsal surface of forearm adopts a dinner fork shape

Question 25

smith’s fracture

Answer 25

fall onto flexed wrist
direct blow to posterior surface of distal forearm
anterior and proximal displacement of distal radial fragment

Question 26

scaphoid fracture

Answer 26

most vulnerable carpal to fracture
usually due to fall on outstretched arm with hand in abducted position
normal scaphoid anatomy:
-proximal pole
-wait
-distal pole

arterial blood supply VERY important

Question 27

scaphoid - arterial blood supply

Answer 27

main arterial blood supply: dorsal scaphoid branch of the radial artery

enters scaphoid at the waist, turns proximally to supply 80% of the bone

the waist is the weakest part of the scaphoid. fracture here can interrupt arterial blood from reaching proximal 80% of bone

distal 20-30% supplied by branches from superficial palmar arch

Question 28

scaphoid - avascular necrosis (AVN)

Answer 28

waist is weakest part of scaphoid, fracture here can interrupt arterial blood supply from reaching proximal 80% of bone

without arterial blood supply [avascular], proximal 80% of bone dies [becomes necrotic] … leading to avascular necrosis [AVN]

Question 29

where is the scaphoid

Answer 29

'’hitch hiking’’ position
scaphoid at base of hollow made by thumb tendons
scaphoid found in floor of ‘ anatomical snuffbox’’

Question 30

thumb movements

Answer 30

capable of wide range of movements due to its carpometacarpal joint (synovial, saddle shape)

The thumb CMC joint is the joint most commonly affected by osteoarthritis

The thumbs MCP joint is a synovial hinge joint

Thumbs only IP joint is a synovial hinger joint

Question 31

movement of the digits 2-5

Answer 31

proximal + distal IP joints:
- abbreviated to PIP + DIP j
- hinger synovial joints
- flexion + extension

MCP joints:
- knuckles
- condyloid synovial joints
- flexion + extension
- abduction + adduction
- circumduction

CMC joint
- plan synovial joint

Question 32

surface anatomy of wrist + hand

Answer 32

styloid processes of the radius and ulna

Question 33

anatomical snuffbox - floor

Answer 33

scaphoid proximally
trapezium distally

Question 34

anatomical snuffbox - boundaries

Answer 34

extensor pollicis longus
extensor pollicis brevis
abductor pollicis longus