Wrist & Hand
Wrist movements occur both at the wrist (radiocarpal) joint and the midcarpal joint. Flexion is predominantly at the midcarpal joint, and produced by the long digital flexor tendons, flexor carpi radialis and flexor carpi ulnaris. Extension is predominantly at the radiocarpal joint; it is produced by the long digital extensors, combined with the radial and ulnar carpal extensors. Abduction occurs mainly at the midcarpal and adduction mainly at the radiocarpal joint, they are produced mainly by the flexor and extensor carpi ulnaris (adduction), and extensor carpi radialis longus and brevis, and flexor carpi radialis (abduction).
Normal hand function is dependent on the integrated activity of many muscles and joints, as well as intact sensory and motor function (page 348). The details of the small muscles of the hand are considered in table 9.
Table 9 Muscles of the hand
This activity is assessed throughout the examination in the patient’s ability to unbutton and undress, and noting any difficulty or associated pain. Other practical measures to assess ability are:
Holding a pen, scalpel or screwdriver, the pinch-grip of flesh or coins, opening a jam jar or carrying a brief case (figure 53a–g).
Note any wasting, particularly of the first dorsal interosseus (figure 54), and the interossei deep to the extensor tendons.
In the anatomical position (with the palm facing forwards in full supination – figure 55a), the radial and ulnar styloid processes can be palpated. The radial styloid is approximately 1cm distal to that of the ulna. This is an important relationship, since fractures of the lower end of the radius are common, and impaction displaces the radial styloid proximally, so that the two styloid processes often end up at the same level.
In pronation (figure 55b), the radial styloid process is still palpable, but on the medial side of the wrist – it is the head, and not the styloid process, of the ulna that is now palpable on the lateral side. Injection into the wrist joint is from the dorsal surface, just medial to the dorsal tubercle, where the extensor pollicis longus turns laterally around it (figure 56).
1. Radial styloid 1. Head of ulna
2. Ulnar styloid 2. Radial styloid
Inspect the wrist for erythema, swelling, deformity and muscle wasting. A boggy swelling may signify the presence of synovitis or an effusion. When abnormalities exist, palpate for tenderness and observe active movement, and examine resisted and then passive movement, of each joint. Palpate the dorsal surface of the wrist with both thumbs, supporting the joint underneath with your index fingers.
The anatomical snuffbox (figure 57) overlies the lateral aspect of the wrist joint, the scaphoid, trapezium and the base of the first metacarpal.
Figure 57 Anatomical snuff box
1. Extensor pollicis longus
2. Distal end of radius
3. Radial nerve
6. Cephalic vein
8. Base of first metacarpal
9. Radial artery
10. Extensor pollicis brevis
Fractures of the scaphoid can be easily missed and an important physical sign is persistent tenderness over the bone at this site.
Examine the lateral aspect of the wrist joint (figure 58a), palpate and apply pressure to the scaphoid (figure 58b) to search for tenderness. This is a common site for synovitis of the tendons on either side of the snuffbox, after unusual activity (De Quervain’s synovitis). The tendons may require injection: abductor pollicis longus and extensor pollicis brevis (figure 59a) and extensor pollicis longus (figure 59b).The flexor retinaculum is attached to four palpable bony structures at the wrist (figure 60a,b).
It is only the size of a postage stamp, but has important clinical implications, as the median nerve passes beneath it and can be compressed, particularly after injury or with arthritic changes of the wrist or carpal bones. The proximal bony attachments are the tubercle of the scaphoid and the pisiform bone, and the distal the ridge of the trapezium and the hook of the hamate. Palpation at these sites also identifies other abnormalities of the carpal bones; dorsal pressure may locate tenderness, in particular note tenderness or deformity of the lunate bone; it is subject to dislocation.
1. Right thumb on tubercle of scaphoid 2. Ridge of trapezium
6. Left thumb on pisiform
7. Bases of metacarpals
9. Hook of hamate
1. Right thumb on tubercle of scaphoid
2. Left thumb on pisiform
3. Ridge of trapezium
4. Hook of the hamate
Apply pressure over the palm of the hand where the median nerve passes from under the flexor retinaculum (figure 61a). Injection of the nerve and the carpal tunnel may be proximal or distal to the retinaculum (figure 61b,c). Further distally in the palm, there may be thickening of a Dupuyteren’s contracture (page 11) or the palpable nodule and clicking of a trigger finger. The latter may respond to injection (figure 61d), but often requires surgical incision of the tendon sheath.
Side to side pressure across the metacarpal heads or anteroposterior over individual joints (figure 62a,b), may elicit tenderness and can be early signs of inflammatory disease.
The interphalangeal joints are very superficial and pressure can be applied across them to detect tenderness (figure 62c,d).
Gently passively flex and extend the patient’s fingers while palpating the flexor tendons to detect crepitus or restriction of movement from tenosynovitis.
When assessing the grip, note that the flattened fingers angle towards the line of the middle finger (figure 63a). When making a fist, the hand is more compact, functional and angular (figure 63b).
When assessing the power of the grip, compare the two sides; give the patient two fingers to grip in each hand (figure 63c – three fingers could end up with a personal crush injury!).
Examine wrist flexion by asking the patient to approximate the dorsum of their hands together and to flex the wrists, it is approximately 90 degrees (figure 64a–c).
Extension of the wrist joint is from 85-90 degrees; ask the patient to put their palms together in the praying position, and then extend the wrists (figure 64d–f).
Radial and ulnar deviation at the wrist are about 20-50 degrees and 90 degrees respectively (figure 65a,b). Similar ranges should be achieved in active and passive movements.
The combined action of the long flexors and extensors, linked by the lumbricals, produces flexion at the metacarpophalangeal joints and extension at the interphalangeal joints. Assessing the power of this movement reflects lumbrical activity; they are supplied by both median and ulnar nerves, on the respective sides of the hand (figure 66a,b).
Flexion of the metacarpophalangeal joints, with the fingers straight, is to 90 degrees; flexion at the proximal interphalangeal joint is approximately 90 degrees but increases to 120 degrees when the distal interphalangeal joint is fully extended. Flexion of the distal interphalangeal joint is approximately 80 degrees. Active flexion is assessed by asking the subject to make a fist; resisted flexion is by pulling on clawed fingers, either of the subject’s two hands or against your own claw (figure 67).
Extension of the proximal and distal interphalangeal joints is to zero (figure 68a–d). There should be no hyperextension at the proximal interphalangeal joint, but often some laxity at the distal. The capacity to hyperextend should be noted, as hypermobility of the joints may indicate Marfan’s or Ehlers-Danlos syndromes.
Abduction of the little finger and thumb can be compared on the two sides by pressing the equivalent digits together, with a rigid outstretched hand (figure 69a,b).
Assess the power of opposition of the thumb to the pulp of the fingers by trying to separate this contact (figure 70a). Figure 70b–e shows the examination of other thumb movements.
Gripping between the thumb and the side of the index finger is supported by the adductor pollicis muscle (the only thenar muscle to be supplied by the ulnar nerve). In ulnar nerve injury, weakness of this muscle is compensated for by flexion at the interphalangeal joint, as seen in the right thumb of the subject on the left in figure 71; this is known as Froment’s sign.
The dorsal interossei abduct the fingers (DAB); assess their power by asking the patient to keep the fingers spread apart against resistance (figure 72a,b). The palmar interossei adduct (PAD); this is tested by gripping paper between adjacent fingers (figure 73).