Function Anatomy and Clinical Conditions of the Hand and Wrist

Question 1

Which 4 sets of joints are in the hand?

Answer 1

Distal interpharyngeal, proximal interpharyngeal, metacarpopharyngeal and carpometacarpal.

Question 2

What makes up the blood supply of the hand and what are the arches?

Answer 2

The radial and ulnar arteries have branches that meet at the superficial palmar arch (then common digital arteries) and the deep palmar arch, which is more proximal. The arches are superficial/deep to the long flexor tendon.

Question 3

What is an Arterial Blood Gas for and how would one test if the radial artery was appropriate for use?

Answer 3

ABG taken to see the effect of breathing e.g. Oxygen, carbon dioxide, pH. Vascularity is checked with the Allen’s test - the hand is elevated and the fist is clenched for 30 seconds with pressure applied over both arteries (ulnar and radial) to occlude, the hand is the opened and should be blanched. The ulnar artery is released and blood should return (if the ulnar supply insufficient then may be unsafe to cannulate radial).

Question 4

Palmar skin is _______, so after a graft, it will never work as well. It is for protection and ____________ for grasping and _________ and must move with underlying _______. As long as the __________ _________ is still present, a nail will regrow - they’re useful for grip etc. The palmar skin is thick with epidermis projections into a thin dermis area - it has no _____.

Answer 4

Unique
Function
Feeling 
Joints
Germinal matrix
Hair

Question 5

What is the motor innervation of the hand?

Answer 5

All the internal muscles of the hand are supplied by the ulnar nerve, apart for LOAF, which are supplied by the median nerve:
Lateral 2 lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis - the last 3 make up the thenar eminence.

Question 6

What is the sensory innervation of the hand?

Answer 6

Median nerve supplies lateral 2/3 of palm and the tips of the radial 3 and 1/2 digits on the dorsal side. (Palmar cutaneous branch comes off before palmar digital branch).
Ulnar nerve - the ulnar 1/3 of palm and ulnar 1/3 on dorsal side.
Radial nerve - the radial 2/3 of dorsal side, excluding finger tips.

Question 7

In Carpal Tunnel Syndrome the median nerve gets trapped, what do the lumbricals so and how is the action of APB tested?

Answer 7

The lumbricals flex at the metacarpal-pharyngeal joints and extend the inter pharyngeal joints.
Abductor pollicis breviary is tested by resisting movement to see if it has atrophied from lack of movement.

Question 8

What passes through the carpal tunnel and what are the borders?

Answer 8

4 tendons of flexor digitorum superficialis and 4 tendons of flexor digitorum profundus, tendon of flexor pollicis longus and the median nerve.
The flexor retinaculum, is thick connective tissue which makes the roof of the carpal tunnel. The carpal arch is formed laterally by the scaphoid and trapezium tubercules and medially by the hook of the hamate and pisiform.

Question 9

How does the ulnar nerve enter the hand?

Answer 9

The ulnar nerve passes into the hand superficial to the flexor retinaculum, through Guyon’s canal.

Question 10

What is Froment’s sign?

Answer 10

A weak pinch grip. If the ulnar nerve is compromised, then there will be interpharyngeal joint flexion as flexor pollicis longus is dominant over adductor pollicis. Ulnar nerve may be trapped at medial epicondyle.

Question 11

How do the flexor tendons attach to the digits? What blood supply do they use?

Answer 11

Flexor superficialis tendons split into 2 and attach on the middle phalanx, so there’s an opening for digitorum profundus to do through and attach to the distal phalanx.
They use the blood supply to the bone - the vinculi health with this adherence and vascularisation.

Question 12

Why are there sheaths with pulleys at the levels of the interpharyngeal joints?

Answer 12

To avoid ‘bow stringing’ and loss of motion; they keep the tendons opposed to the bone.

Question 13

What acts as a bridge between the extensor tendons and the flexor tendons?

Answer 13

The lumbricals.

Question 14

Which carpal bone acts as the main point of carpal-radial articulation at the wrist and how is it connected to the rest of the carpals?

Answer 14

The lunate, which is connected to the rest of the carpals by the scaphoid (vulnerable to injury).

Question 15

Which are the more mobile bones on the distal row of carpals?

Answer 15

The trapezium and trapezoid are more mobile, with the capitate and the hamate not moving much.

Question 16

At which position in the scaphoid is a fracture mostly likely to result in malunion and why?

Answer 16

In the proximal scaphoid, as it has the poorest blood supply. If the scaphoid-lunate ligament is form and the gap between gets too big, then there will be pain and it may need more active repair.

Question 17

What is tenosynovitis?

Answer 17

Inflammation of the synovium (fluid filled space), surrounding a tendon.
In tenosynovitis, the inflammation can be of the flexor tendons of the hand - the 1st dorsal compartment in the anatomical snuffbox leads to pain and swelling.

Question 18

What is Finkelstein’s test?

Answer 18

Grab the thumb and ulnar deviate sharply. Tenosynovitis is recognised if there is sharp pain along the distal radius.
You may then want to splint, do surgery or give steroids (an injection can cause hypopigmentation).

Question 19

What is Dupuytrens disease?

Answer 19

Dupuytrens disease is a functional defecitnmore common in Caucasians, predominantly involving the genetic build up of scar tissue in the palm. There may be a single contracture of a proximal interpharyngeal joint >30 degrees (associated with alcoholic liver disease and diabetes), which can get in the way. There is no cure, but there are currently collagenase trials.

Question 20

What is Cubital Tunnel Syndrome?

Answer 20

Ulnar compression at the elbow.

Question 21

Explain tendon avulsion.

Answer 21

Flexor digitorum profundus has the strongest grip and so may snap of if something is pulled away - it could pull of a chunk of the distal phalanx, leaving one finger extended when the patient tries to make a fist.

Question 22

What is a Boxer’s fracture?

Answer 22

The commonest metacarpal fracture of of MC5 and this is at its neck, often after a punch.

Question 23

What type of arthritis is symmetrical, worse at night and can cause ulnar deviation as well as swelling and stiffness of joints?

Answer 23

Rheumatoid arthritis.

Question 24

CRPS and RSD are both describing what problematic reaction of the body after an injury?

Answer 24

Complex Regional Pain syndrome/Reflex Sympathetic Dystrophy syndrome.
Normal pain signals are sent after an injury, so the affected area is rested, but abnormal signals even when healing lead to stiffness and swelling as the site is not moved. Major injury could become a chronic problem so treat with physiotherapy and pain killers. Most common in women and the upper limb.