Other

Question 1

Functions of the hand

Answer 1

1. Communication (hand signals)
2. Manipulation (e.g. writing)
3. Sensation
4. Protection
5. Stability (aids balance)

Question 2

Stability of wrist

Answer 2

> Pronator quadratus
many tendons crossing the wrist
tendons held in place by flexor/extensor retinaculum
ligaments (radiocarpal + intercarpal) ant/post, med/lat support

Question 3

Carpal Tunnel

Answer 3

> roof: flexor retinaculum
floor: carpal bones
Contents: 4 Flexor digitorum profundus tendons
: 4 flexor digitorum superficialis tendons
: flexor pollucis longus tendon
: Median nerve
* Flexor Carpi radialis had own compartment
Carpal tunnel syndrome = compression of median nerve - leads to pain + numbness in palmar lateral half of hand + fingertips of thumb, finger 1, finger 2

Question 4

Retinaculum of wrist

Answer 4

Flexor
> Tough band of connective tissue - square shaped
> proximal - tubercle of scaphoid to pisiform
> distal - tubercle of trapezium to hook of hamate
- can be considered an accessory ligament

Extensor
> connective tissue band
> from anterior border of lower radius 
> to styloid process of ulna,
        triquetrum
         pisiform

Question 5

Extensor compartments of wrist

Answer 5

> 6 tunnels that transmit long extensor tendons from forearm to hand
> on posterior aspect of wrist, lined with synovial sheath and separated by fibrous septa
Compartment 1 (radial aspect of wrist)
- extensor pollicis brevis
- abductor pollicis longus
Compartment 2
- extensor carpi radialis longus + brevis
Compartment 3 (separated from 2 by lister's tubercle)
- extensor pollucis longus 
Compartment 4
- extensor digitorum
- extensor indices
Compartment 5
- extensor digiti minimi 
Compartment 6 (medial aspect of wrist)
- extensor carpi ulnaris

Question 6

Tendon sheaths of wrist

Answer 6

> prevent friction with retinaculum
flexor
- 8 tendons of fdp + fds share a synovial sheath
- flexor pollucis longus has own sheath
extensor
- each compartment has own synovial sheath

Question 7

Nerve issues with hand

Answer 7

> median nerve = dexterity loss
- thenar muscles + finger flexors are affected

> Ulnar nerve = clawed hand
- hypothenar muscles + interossei + adductor pollicis = affected

> Posterior interosseous nerve = dropped wrist
- epl/ epb/ apl + wrist extensors affected

Question 8

Arches of the hand

Answer 8

> Transverse
1. Carpal arch - concave
- little movement
2. Metacarpal (heads) arch - can widen + flatten (stability + mobility)
Longitudinal arches
- run through each digit
- assumes wide variety of shapes
Oblique arches
- by thumb to opposing finger
- creates palmar gutter from base of hypothenar eminence to head of 2nd MC

Question 9

Prehension (grip)

Answer 9

1. Power grips
   > palmar grip:
   - most powerful as involves wrist/ long flexors/ thenar muscles
   - thumb acts as buttress and fingers close around object
   > Hook grip:
   - thumb is not involved, grip = between fingers + palm
   - mainly static work of long flexors
2. Precision grips (require good sensation)
   > Pincer = tip to tip (most precise)
   > Pad to pad = most common
   > key - thumb to lateral side of index (middle phalanx)
   - strongest
   > adduction - between fingers (weak + not precise)

Question 10

Palmar aponeurosis

Answer 10

> Triangular sheet of deep fascia in centre of palm
apex from flexor retinaculum and tendon of palmaris longus
to base = dermis of skin and bases of each digit
gives firm attachment for skin - improves grip
protects underlying vessels/tendons/nerves

Question 11

Extensor hood a.k.a digital dorsal expansion

Answer 11

> triangular aponeurosis by which the extensor tendons attach to the phalanges
base attaches to palmar plate around side of metacarpal and proximal phalanx
tip then inserts into base of distal phalanx
extensor digitorum forms central component and inserts onto middle phalanx but sends slips to edge of extensor hood to act on DIP
extensor indicis and extensor digiti minimi then insert onto ulna side of respective extensor hoods
With interossei and lumbricals forming the thicker edge attachments