Hand

Atlas References

• Netter: 442–469

• McMinn: 154–169

• Gray's Atlas: 426–429, 440–456

Before You Begin

Palpation

Flex and extend your digits, noting the movements of the tendons beneath the skin. On the dorsal side of your hand, identify the tendons of the extensor digitorum muscle. At the flexor aspect of the palm, note the distal skin crease (crease between wrist and forearm), marking the proximal edge of the flexor retinaculum ( Fig. 9.1 ).

• At the ulnar side of the distal skin crease, palpate the pisiform bone. At the radial side of the distal skin crease, palpate the scaphoid bone. Immediately beneath the radial and ulnar sides of the distal skin crease, palpate the radial and ulnar styloid processes , respectively.

• By flexing the closed fist against resistance, you should be able to identify several tendons at the anterior wrist, from medial to lateral: the flexor carpi ulnaris, flexor digitorum superficialis, palmaris longus, and flexor carpi radialis. However, the most prominent tendons are those of the palmaris longus, lying at the midline, and the flexor carpi radialis, lying in the radial side. Lateral to the tendon of the flexor carpi radialis, you can palpate the radial artery. The pulsations of the ulnar artery are more difficult to detect but usually are felt about 3 cm proximal to the pisiform bone, lateral to the flexor carpi ulnaris muscle. Note the thenar and hypothenar eminences, which contain muscles of the 1st digit and the 5th digit, respectively.

On the dorsum surface of the hand, extend the 1st digit, noting the tendons of the abductor pollicis longus (to base of 1st metacarpal bone), the extensor pollicis brevis (to base of 1st phalanx), and the extensor pollicis longus muscles (to base of distal phalanx of 1st digit) forming the “anatomic snuffbox” ( Fig. 9.2 ). This anatomic area is important because the radial artery lies on the scaphoid bone and passes to reach the dorsum of the 1st digit.

If the dorsum of the hand has not been dissected already on your cadaver as it was in Chapter 8 , then refer to Chapter 8 , Fig. 8.12, Fig. 8.13, Fig. 8.14, Fig. 8.15, Fig. 8.16 before proceeding to the palmar dissection ( Fig. 9.3 ).

Palmar Hand

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  Make a similar midline incision on the palmar surface, starting from the distal palmar crease to the base of the 3rd digit ( Fig. 9.4 ). Make a second midline incision on the palmar surface of each digit. Join these with transverse incisions at the bases of the digits.

  

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  With additional incisions as necessary, reflect and remove the skin from the hand ( Fig. 9.5 ).

  

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  After removal of the skin on the palmar surface of the hand, trace the continuation of the palmaris longus muscle to the palmar aponeurosis (see Fig. 9.5 ).

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  Note the thenar eminence with the flexor pollicis brevis and abductor pollicis muscles ( Fig. 9.6 ).

  

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  Lift the palmar aponeurosis ( Fig. 9.7 ) and with the aid of dissecting scissors separate it from the underlying structures ( Fig. 9.8 ).

  
  

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  With scissors, cut the attachments of the longitudinal bands from the bases of the proximal phalanges. Reflect the palmaris longus muscle and the palmar aponeurosis toward the forearm ( Fig. 9.9 ).

  

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  After removal of the palmar aponeurosis, start exposing the superficial palmar arch ( Figs. 9.10 and 9.11 , Plate 9.1 ).

  
  
  

Dissection Tip

The superficial palmar arch is related to the superficial venous arch, as well as with common palmar digital branches of the median nerve. With scissors, separate the nerves from the superficial palmar arch (see Figs. 9.10 to 9.12 ). Also, remove any venous structures from this area.

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  Immediately after its passage through the carpal tunnel, the median nerve gives rise to several smaller branches: the recurrent branch of the median nerve and the common palmar digital branches. At this point in the dissection, identify the common palmar digital branches of the median nerve running alongside the common palmar digital arteries ( Fig. 9.13 , Plate 9.2 ).

  
  

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  Continue the dissection toward the phalanges, and expose the separation of the common palmar digital branches of the median nerve into proper palmar digital nerves of the digits.

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  Similarly, expose the site at which the common palmar digital arteries give rise to palmar digital arteries ( Fig. 9.14 ).

  

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  Clean away the fascia investing the abductor and flexor digiti minimi muscles over the hypothenar region.

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  Continue the removal of fat and remnants of the palmar aponeurosis at the medial aspect of the palm, the hypothenar eminence (see Fig. 9.8 ). Identify the flexor digiti minimi and the abductor digiti minimi muscles (see Fig. 9.12 ). Expose the palmar digital branches to the 5th digit and medial half of the 4th digit (see Fig. 9.14 ).

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  Trace the palmar digital branches to the 5th digit and medial half of the 4th digit toward their origin from the superficial branch of the ulnar nerve ( Fig. 9.15 ).

  

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  Remove the deep fascia at the ulnar side of the wrist, and using scissors ( Fig. 9.16 ), expose the superficial branch of the ulnar nerve ( Fig. 9.17 ). The ulnar artery and nerve travel lateral to the pisiform bone to enter the palm.

  
  

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  Expose the superficial ulnar artery and nerve toward the pisiform bone ( Fig. 9.18 ).

  

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  Clean the adipose tissue and remnants of the palmar aponeurosis surrounding the superficial palmar arch distally to the carpal tunnel and flexor retinaculum (see Fig. 9.18 ).

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  Expose the ulnar artery and clean the surface of the flexor retinaculum ( Fig. 9.19 ).

  

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  To free up the superficial palmar arch and nerve structures from the underlying long flexor tendons, use scissors to incise the fibrous tendinous sheaths longitudinally. Identify tendons of flexor digitorum superficialis and profundus muscles ( Fig. 9.20 ).

  

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  Immediately distal to the pisiform bone and lateral to the flexor retinaculum, expose the division of the ulnar artery and nerve into deep and superficial branches ( Fig. 9.21 ).

  

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  The deep branches dive deeply between the abductor and flexor digiti minimi muscles of the 5th digit.

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  Carefully expose the flexor retinaculum and identify its borders. Look for the palmar cutaneous branch of the median nerve ( Fig. 9.22 ).

  

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  Pass a probe or scissors underneath the flexor retinaculum in the carpal tunnel ( Fig. 9.23 ).

  

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  Leave the probe within the carpal tunnel and with scissors divide the flexor retinaculum on top of the probe ( Fig. 9.24 ). This retinaculum is transected by inserting the scissors into the carpal tunnel upwardly, cutting in a proximal-to-distal manner.

  

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  Remove the probe, and retract the flexor retinaculum to expose the median nerve and tendons of the flexor digitorum superficialis ( Figs. 9.25 and 9.26 ).

  
  

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  Remove the connective tissue sheath over the median nerve and the underlying flexor digitorum superficialis muscle ( Fig. 9.27 ).

  

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  Continue exposing the median nerve within the carpal tunnel. Identify the recurrent branch of the median nerve ( Fig. 9.28 ). Finish the exposure of the common palmar digital branches of the median nerve.

  

Dissection Tip

In some cases, branches of the superficial palmar arch travel close to the common palmar digital branches or penetrate them. Use special care when you dissect these structures ( Fig. 9.29 ).

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  With forceps, retract the abductor digiti minimi muscle laterally, and expose the flexor digiti minimi brevis and the opponens digiti minimi muscles ( Fig. 9.30 ).

  

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  You may cut and reflect the abductor digiti minimi near its origin to expose the underlying opponens digiti minimi muscle.

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  Trace the superficial palmar arch laterally in the space between the 1st digit and the 2nd digit.

Dissection Tip

There is usually an anastomosis between the superficial palmar arch and a branch of the radial artery, the radialis indicis, and a branch to the 1st digit, the princeps pollicis ( Fig. 9.31 ).

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  Identify the abductor pollicis brevis muscle, lying at the lateral side of the base of the 1st phalanx of the 1st digit (see Fig. 9.31 ).

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  Medial and next to the abductor pollicis brevis muscle, identify the flexor pollicis brevis muscle, which is passing along the radial side of the tendon of the flexor pollicis longus muscle. Retract the abductor pollicis brevis muscle laterally from the flexor pollicis brevis muscle, and identify the opponens pollicis muscle ( Fig. 9.32 ). Flexor pollicis brevis has two heads. Its deep head can be mistaken for the opponens pollicis brevis. Reflect both heads.

  

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  Finally, identify the adductor pollicis muscle, which can be seen between the base of the 2nd and 1st digits.

Dissection Tip

You may also transect the abductor pollicis brevis and identify the opponens pollicis muscle just underneath it ( Fig. 9.33 ). Another way to distinguish the opponens pollicis brevis muscle from the abductor pollicis brevis and the flexor pollicis muscles is its insertion point. The opponens pollicis brevis muscle inserts alongside the 1st metacarpal.

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  On the dorsum of the hand, clean and expose the tendinous insertions of abductor pollicis longus, the extensor pollicis brevis, and the extensor pollicis longus ( Fig. 9.34 ).

  

Dorsal Hand

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  Identify the radial artery and trace it as it passes between the two heads of the 1st dorsal interosseous muscle (see Fig. 9.34 ).

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  Observe the radial side of the 2nd digit. At the level of the proximal interphalangeal joint, note the extensor mechanism splitting into three parts. Note that one of these parts, the lateral bands, to which the extensor tendons contribute, eventually unite with the transverse metacarpal ligament ( Fig. 9.35 ).

  

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  At the palmar side of the digits, observe the fibrous synovial sheaths surrounding the tendons of the long flexor muscles ( Fig. 9.36 ).