Problems in the upper limb may arise from nerve entrapment in the neck, so always check the neck when examining the upper limb. Do not forget to use both sides for comparison and to check distal neurovascular status.

• In trauma a clear description of how the limb was injured will usually give the likely diagnosis.
  
• In chronic problems, check for early morning pain and stiffness (inflammatory joint disease).

Shoulder

The acromion (the point of the shoulder) is much more prominent when the shoulder has dislocated. Even after relocation the acromion may appear prominent again after some weeks as there is usually wasting of the deltoid muscle over the shoulder due to bruising of the axillary nerve. A prominent lump over the end of the clavicle is the result of injury to the acromioclavicular joint which may subluxate and then become arthritic.

Elbow

Hard lumps may form on the back of the elbow (gouty tophi), also a favourite site for psoriasis (silvery scaly skin on the extensor surface). Any injury to the elbow tends to leave it stiff with loss of flexion and extension.

Wrist

Swelling around the wrist is common in inflammatory joint disease.

Hand and fingers

• Wasting of the base of the thumb occurs if there is damage to the median nerve, especially at the wrist.
  
• Damage to the ulnar nerve produces wasting in the clefts between the fingers.
  
• Inflammatory arthritis affects the hands in particular, producing a number of characteristic deformities (see Chapter 23).
  
• Dupuytren’s contracture commonly affects the little and then the ring finger, curling them into the palm (see page 22).

The clavicle, acromioclavicular joint and shoulder joint are close to the skin and so are easy to feel. Similarly the bones and joints of the elbow, wrist and hand can all be felt through the skin. Lumps and areas of tenderness can be identified and linked to the underlying anatomical structures.

The ulnar nerve can be felt in the groove between the olecranon and the medial epicondyle at the back of the elbow. If it is tender and sends shock waves down the arm when pressed or tapped, it may be inflamed because it is getting trapped in the groove. Similarly the median nerve may get trapped at the wrist under the flexor retinaculum (see carpal tunnel syndrome below).

• Shoulder. The functional range of the shoulder can be checked by asking the patient to put their hands behind their head, then straight up, straight forward, out to the side and finally bring the hand up the back from below. Use both sides for comparison.
  
• Elbow. If the arms are then held straight forward, flexion and extension of the elbows can be compared by watching the patient from the side.
  
• Forearm. Finally, with the upper arms by the side and the forearms facing straight forward, pronation and supination of the forearm can be checked without the patient being able to use the shoulder to confuse the measurements.
  
• Wrist. Wrist movements can be checked by asking the patient to get into a prayer position then to raise the elbows as far as possible. The exact opposite manoeuvre (pointing the fingers down) will check wrist flexion.
  
• Finger. Finger movements can be checked quickly by first asking the patient to make a fist, then unroll the hand to a flat palm and then touch each finger tip to the tip of the thumb in turn. A trigger finger can be diagnosed by finding one finger is late in extending and then goes with a jump as the thickened flexor tendon (which can be felt) passes in to the narrow flexor tendon tunnel in the finger.

Resisted movements

• The thumb down test is diagnostic of rotator cuff inflammation. The patient should hold the arms out straight with each arm facing 45 degrees forward of straight out sideways. The hand is set so that the thumb is pointing down. If there is a sharp pain in the shoulder when the examiner pushes the hand down against resistance then the test is positive.
  
• The apprehension sign is a feeling of deep unease that patients feel when the shoulder is pushed into extension with the upper arm abducted and the forearm externally rotated. It is strong evidence that the shoulder has been dislocated in the past, and is still unstable.
  
• Getting the patient to grip your fingers tests the power of both flexors and extensors of the wrist (as the fingers cannot flex properly unless the wrist can be held extended).
  
• Testing the patient’s ability to spread their fingers apart checks the power of the intrinsic muscles of the hand (ulnar nerve).

In the case of suspected nerve damage you will need to plot areas of loss of sensation as well as weakness and wasting of individual muscles. Then, by reference to the distribution of impaired sensation, you should be able to work out which nerve(s) are damaged and at which level. Loss of sensation in the hand is best determined using two point discrimination, using the other side for comparison.

Carpal tunnel syndrome

Tapping with your finger tip over the front of the patient’s wrist (where the median nerve passes under the flexor retinaculum) produces ‘electric shocks’ running down into the fingers if the median nerve is being compressed (Tinel’s test). Phalen’s test involves flexing the patient’s wrist while pressing hard on the median nerve at the front of the wrist. After 30 seconds the patient will find their fingers going numb.

Ulnar neuritis

The ulnar nerve frequently gets trapped in the groove on the medial side of the elbow as it passes round the back of the joint. Pressure or tapping on the irritated nerve will produce electric shocks down the arm into the ulnar side of the hand.

The most problematic of the carpal bones is the scaphoid whose blood supply enters the distal pole and tracks proximally. If a young person falls hard onto the outstetched hand the scaphoid can fracture across its middle (the waist) compromising the blood supply to the proximal pole (see Chapter 9). The blood supply to the hand is usually via two arteries (the radial and the ulnar) which anastomose through a proximal and distal palmar arch. Arterial puncture for blood gas analysis can be performed from the radial artery, but first Allen’s test must be performed to check that the ulnar artery is functioning. Otherwise damage to the radial artery might compromise blood supply to the hand.

The main nerves of sensation to the hand are the median nerve which supplies the radial three and one half fingers while the ulnar nerve supplies the little finger and half of the ring finger. The motor supply within the hand is mainly the ulnar nerve while the median nerve supplies the thenar eminence of the thumb (especially opponens).

The flexor tendons travel up the fingers in sheaths. Inflammation can narrow the mouth of these flexor sheaths and lead to thickening of the flexor tendons (see trigger finger, Chapter 7).

The structures are so tightly packed in the hand that as a general rule if a flexor tendon to finger is cut it is very likely that the digital nerve has been cut too. It can be difficult to diagnose an isolated superficial tendon injury because the deep tendon travels right to insert in the distal phalanx. However flexor digitorum profundus is a mass action muscle, so its action can be blocked by holding the other fingers extended.