Anatomy of the hand and wrist (clinical relevance)

Question 1

What names are given to each finger?

Answer 1

Thumb - D1

Index - D2

Long - D3

Ring - D4

Little - D5

Question 2

Name the corresponding hand bone groups

How many carpal bones are there?

Answer 2

8 carpal bones

Question 3

Name the joints that exist between bones in the hand

How many of each are there?

Answer 3

Names of joints are just the two bone groups mashed into one.

4x Distal interphalangeal joints (DIP)

4x Proximal interphalangeal (PIP) joints

1x Interphalangeal (IP) joint (in the thumb)

5x Metacarpophalangeal (MCP) joints

5x Carpometacarpal (CMC) joints

Question 4

Name each of the carpal bones

Answer 4

The important ones are the:

• Scaphoid
• Trapezium
• Lunate

Question 5

What is the clinical relevance of the blood supply to the scaphoid bone?

Answer 5

The scaphoid bone has a retrograde blood supply (ie blood vessels to it go backwards) from the radial artery

When fractured - the proximal end of the scaphoid (which is at the end of the blood vessels) is liable to avascular necrosis

The more proximal the fracture - the more likely AVN

Question 6

What is the anatomical snuffbox?

What is it’s clinical relevance?

Answer 6

Triangular area of the hand between the Extensor pollicis longus (EPL), Extensor pollicis brevis (EPB) and the abductor pollicis longus (AP)

You can palpate the scaphoid through this deepening - which means in scaphoid fractures, palpation causes pain to the patient

Question 7

What can be palpated in the anatomical snuffbox?

Answer 7

Radial artery

Radial styloid process

Scaphoid

Trapezium

Base of the 1st metacarpal

Question 8

Name the superficial flexors of the fingers (that are on the forearm)

Answer 8

Pronator teres - Index finger

Flexor carpi radialis - Middle finger

Palmaris longus - Ring finger (missing on some people)

Flexor carpi ulnaris - Little finger

PFPF

Question 9

Identify the superficial flexors of the forearm?

Answer 9

Question 10

What two flexor tendons are attached to the fingers?

Answer 10

Flexor digitorum superficialis

Flexor digitorum profundus

Question 11

How would you test to see if there is damage to the flexor digitorum profundus?

Answer 11

The FDP is the only tendon that acts on the Distal interphalangeal joint

(as it attaches to the distal phalanx)

To test - isolate the distal phalanx (DIPJ) and ask to flex

Question 12

How would you test the Flexor digitorum superficialis?

Answer 12

To test the FDS of a finger - you must straighten out the surrounding fingers by holding them down

This is to isolate the FDS and remove any input from the FDP

This is because the FDP has a shared muscle belly with the other FDPs of other fingers

Question 13

The extensors of the wrist are all covered by the Retinaculum

What is the retinaculum attached to?

Answer 13

Triquetrum & the Pisiform

Carpals^

Question 14

The blood supply to the hand revolves around a Superficial arch and a deep arch

What arteries supply each of these structures?

Answer 14

Superficial arch - Ulnar artery

Deep arch - Radial artery

Question 15

what gives rise to the common digital arteries?

Answer 15

These come off the Superficial arch of the hand

Therefore the Ulnar artery supplies the common digital arteries

NOte that some people don’t have an ulnar artery

Question 16

How do you test to make sure a patient has both Radial artery and ulnar artery supply to their hand

Answer 16

Allens test:

1. Occlude radial & ulnar arteries at the wrist
2. Patient closes hand into fist and holds
3. Patient opens hand - release Ulnar artery
4. Watch if volar surface becomes pink again

If not then only the radial artery exists