The Wrist and Hand-Important Structures Lying in Front of the Wrist-Radial Artery-Tendon of Flexor Carpi Radialis-Tendon of Palmaris Longus (If Present)-Tendons of Flexor Digitorum Superficialis-Tendon of Flexor Carpi Ulnaris-Ulnar Artery-Ulnar Nerve-Important Structures Lying on the Lateral Side of the Wrist-Anatomic Snuffbox-Important Structures Lying on the Back of the Wrist-Lunate-Important Structures Lying in the Palm-Recurrent Branch of the Median Nerve-Superficial Palmar Arterial Arch-Important Structures Lying on the Dorsum of the Hand

The Wrist and Hand

At the wrist, the styloid processes of the radius and ulna can be palpated. The styloid process of the radius lies about 0.75 in. (1.9 cm) distal to that of the ulna.

The dorsal tubercle of the radius is palpable on the posterior surface of the distal end of the radius.

The head of the ulna is most easily felt with the forearm pronated; the head then stands out prominently on the lateral side of the wrist. The rounded head can be distinguished from the more distal pointed styloid process.

The pisiform bone can be felt on the medial side of the anterior aspect of the wrist between the two transverse creases. The hook of the hamate bone can be felt on deep palpation of the hypothenar eminence, a fingerbreadth distal and lateral to the pisiform bone.

The transverse creases seen in front of the wrist are important landmarks. The proximal transverse crease lies at the level of the wrist joint. The distal transverse crease corresponds to the proximal border of the flexor retinaculum.

Important Structures Lying in Front of the Wrist

Radial Artery

The pulsations of the radial artery can easily be felt anterior to the distal third of the radius. Here, it lies just beneath the skin and fascia lateral to the tendon of flexor carpi radialis muscle

Tendon of Flexor Carpi Radialis
The tendon of the flexor carpi radialis lies medial to the pulsating radial artery
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Tendon of Palmaris Longus (If Present)

The tendon of the palmaris longus lies medial to the tendon of flexor carpi radialis and overlies the median nerve

Tendons of Flexor Digitorum Superficialis

The tendons of the flexor digitorum superficialis are a group of four that lie medial to the tendon of palmaris longus and can be seen moving beneath the skin when the fingers are flexed and extended.

 

Tendon of Flexor Carpi Ulnaris

The tendon of the flexor carpi ulnaris is the most medially placed tendon on the front of the wrist and can be followed distally to its insertion on the pisiform bone. The tendon can be made prominent by asking the patient to clench the fist (the muscle contracts to assist in fixing and stabilizing the wrist joint)
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Ulnar Artery

The pulsations of the ulnar artery can be felt lateral to the tendon of flexor carpi ulnaris

Ulnar Nerve

The ulnar nerve lies immediately medial to the ulnar artery

Important Structures Lying on the Lateral Side of the Wrist

Anatomic Snuffbox

The “anatomic snuffbox” is an important area. It is a skin depression that lies distal to the styloid process of the radius. It is bounded medially by the tendon of extensor pollicis longus and laterally by the tendons of abductor pollicis longus and extensor pollicis brevis. In its floor can be palpated the styloid process of the radius (proximally) and the base of the first metacarpal bone of the thumb (distally); between these bones beneath the floor lie the scaphoid and the trapezium (felt but not identifiable).

The radial artery can be palpated within the snuffbox as the artery winds around the lateral margin of the wrist to reach the dorsum of the hand. The cephalic vein can also sometimes be recognized crossing the snuffbox as it ascends the forearm.

Important Structures Lying on the Back of the Wrist

Lunate

The lunate lies in the proximal row of carpal bones. It can be palpated just distal to the dorsal tubercle of the radius when the wrist joint is flexed.

Important Structures Lying in the Palm

Recurrent Branch of the Median Nerve

The recurrent branch to the muscles of the thenar eminence curves around the lower border of the flexor retinaculum and lies about one fingerbreadth distal to the tubercle of the scaphoid

Superficial Palmar Arterial Arch

The superficial palmar arterial arch is located in the central part of the palm and lies on a line drawn across the palm at the level of the distal border of the fully extended thumb

Deep Palmar Arterial Arch

The deep palmar arterial arch is also located in the central part of the palm and lies on a line drawn across the palm at the level of the proximal border of the fully extended thumb

Metacarpophalangeal Joints

The metacarpophalangeal joints lie approximately at the level of the distal transverse palmar crease. The interphalangeal joints lie at the level of the middle and distal finger creases.

Important Structures Lying on the Dorsum of the Hand

The tendons of extensor digitorum, the extensor indicis, and the extensor digiti minimi can be seen and felt as they pass distally to the bases of the fingers.

Flexor and Extensor Retinacula-Flexor Retinaculum-Extensor Retinaculum-Carpal Tunnel-Absent Palmaris Longus-Contents of the Anterior Fascial Compartment of the Forearm-

Flexor and Extensor Retinacula

The flexor and extensor retinacula are strong bands of deep fascia that hold the long flexor and extensor tendons in position at the wrist.

Flexor Retinaculum

The flexor retinaculum is a thickening of deep fascia that holds the long flexor tendons in position at the wrist. It stretches across the front of the wrist and converts the concave anterior surface of the hand into an osteofascial tunnel, the carpal tunnel, for the passage of the median nerve and the flexor tendons of the thumb and fingers.

It is attached medially to the pisiform bone and the hook of the hamate and laterally to the tubercle of the scaphoid and the trapezium bones. The attachment to the trapezium consists of superficial and deep parts and forms a synoviallined tunnel for passage of the tendon of the flexor carpi radialis.

The upper border of the retinaculum corresponds to the distal transverse skin crease in front of the wrist and is continuous with the deep fascia of the forearm. The lower border is attached to the palmar aponeurosis

Extensor Retinaculum

The extensor retinaculum is a thickening of deep fascia that stretches across the back of the wrist and holds the long extensor tendons in position. It converts the grooves on the posterior surface of the distal ends of the radius and ulna into six separate tunnels for the passage of the long extensor tendons. Each tunnel is lined with a synovial sheath, which extends above and below the retinaculum on the tendons. The tunnels are separated from one another by fibrous septa that pass from the deep surface of the retinaculum to the bones.

The retinaculum is attached medially to the pisiform bone and the hook of the hamate and laterally to the distal end of the radius.



The upper and lower borders of the retinaculum are continuous with the deep fascia of the forearm and hand, respectively.

Carpal Tunnel

The bones of the hand and the flexor retinaculum form the carpal tunnel. The median nerve lies in a restricted space between the tendons of the flexor digitorum superficialis and the flexor carpi radialis muscles.

Absent Palmaris Longus

The palmaris longus muscle may be absent on one or both sides of the forearm in about 10% of persons. Others show variation in form, such as centrally or distally placed muscle belly in the place of a proximal one. Because the muscle is relatively weak, its absence produces no disability.

Contents of the Anterior Fascial Compartment of the Forearm

■■ Muscles: A superficial group, consisting of the pronator teres, the flexor carpi radialis, the palmaris longus, and the flexor carpi ulnaris; an intermediate group consisting of the flexor digitorum superficialis; and a deep group consisting of the flexor pollicis longus, the flexor digitorum profundus, and the pronator quadratus

■■ Blood supply to the muscles: Ulnar and radial arteries

■■ Nerve supply to the muscles: All the muscles are supplied by the median nerve and its branches, except the flexor carpi ulnaris and the medial part of the flexor digitorum profundus, which are supplied by the ulnar nerve.