REIDER PART 1
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114_Chapter 4_Hand and Wrist

compared with the thumb. The hypothenar muscles include the abductor digiti minimi (quinti), which forms the medial border of the hand; the flexor digiti minimi (ąuinti); and the opponens digiti minimi (quinti); all are innervated by the ulnar nerve.

Wrist. Where the hand joins the forearm at the wrist, a series of flexion creases is usually visible (Fig. 4-20). The distal flexion crease of the wrist marks the proximal limit of the flexor retinaculum (transverse carpal liga-ment), the tough fascial tissue that forms the roof of the carpal tunnel. On the lateral border of the wrist, the prominence of the base of the first metacarpal is again visible along the lateral base of the thenar eminence. The tendon of the abductor poilicis longus forms the border of the contour of the wrist as it courses distally to insert on the base of the first metacarpal. Moving medially, the next tendon that is usually visible through the skin is that of the flexor carpi radialis (Fig. 4-21 A). Between the abductor poilicis longus and the flexor carpi radialis lies the distal portion of the radial artery. Its pulsations are often visible on careful inspection, and this is a good place to palpate the pulse.

Running just ulnar and parallel to the flexor carpi radialis tendon is the palmaris longus tendon. This struc-ture, present in about 80% of individuals, can be brought out by asking the patient to pinch the tips of the opposed thumb and little finger firmly together with the wrist in slight flcxion (Fig. 4-215). The depression between the flexor carpi radialis and the palmaris longus tendons over-lies the median nerve, which is not itself visible.

At the ulnar side of the wrist, the pisiform bonę cre-ates a bony prominence at the base of the hypothenar eminence. The pisiform is a sesamoid bonę within the flexor carpi ulnaris tendon, a structure that is usually vis-ible and defines the medial border of the wrist. The prominence of both the flexor carpi ulnaris and the flexor carpi radialis tendons may be inereased by having the patient flex the wrist against resistance. The ulnar artery and nerve lie just radial and deep to the flexor carpi ulnaris tendon. The pulsations of the ulnar artery are not normally visible but can be palpated. Between the palmaris longus and the flexor carpi ulnaris is a soft spot. The examiner can feel the tendons move by palpating this spot and asking the patient to flex and extend the fingers. A swelling in this area is indicative of a synovitis that can be idiopathic or rheumatoid synovitis.

The most common mass of the volar wrist is a volar wrist ganglion (Fig. 4-22). These ganglia may vary in size from smali ones, which are only palpable, to larger, visible ones of 1 cm or morę. When visible, they usually appear at the radial side of the wrist.

Ulnar (Medial) Aspect

The ulnar aspcct of the hand and wrist may be most eas-ily inspected by having the patient flex the elbow until the ulnar border of the hand is facing the examiner. This per-spective furnishes fcwer distinguishing landmarks than the other aspects (Fig. 4—23). The superior border of the dorsum of the hand is delincated by the straight contour of the shaft of the fifth metacarpal. Flexion deformities due to acute or malunited boxer^łs fractures of the neck of