REIDER PART 100

90 Chapter 3 Elbow and Forearm

the forearm, sensation to the palmar aspect of the base of the thumb is also affccted. If a morę distal injury occurs, such as a carpal tunnel syndrome, sensation is preserved on the palmar aspect of the base of the thumb because the palmar cutaneous branch of the median nerve is given off before the median nerve enters the carpal tunnel (Fig. 3-41).

Anterior interosseous nerve syndrome has no asso-ciated sensory deficit.

The ulnar nerve supplies sensation to the littlc finger and the ulnar aspect of the ring finger. Any injury to the ulnar nerve at the level of the wrist or morę proximally results in the loss of sensation in this distribution. Injuries that occur morę proximaiły, such as at the elbow, also affect sensation over the dorsal ulnar part of the hand (Fig. 3-42).

The radial nerve supplies sensation to the dorsum of the hand, particularly over the first web space. An injury to the radial nerve at the level of the elbow or above affects sensation in this area (Fig. 3-43).

Special Tests

Nerve Compression Syndromes

Cubital Tunnel Syndrome. The most common nerve compression syndrome occurring about the elbow is the cubital tunnel syndrome involving the ulnar nerve. This syndrome can occur spontaneously or in association with many other factors, such as activities requiring repetitive elbow movements, osteoarthritis, rheumatoid arthritis, fractures and dislocations, cubitus valgus, and instability of the ulnar nerve. Rarely, an anomalous muscle known as the anconeus epitrochlearus crosses the ulnar nerve in the region of the medial epicondyle and may also cause this syndrome. Typical symptoms of cubital tunnel syndrome include achy pain in the medial forearm and paresthesias in the sensory distribution of the ulnar nerve in the hand.

The most common screening test for cubital tunnel syndrome is described in the Palpation section, under Medial Aspect, Ulnar Nerve: percussion of the ulnar nerve between the medial epicondyle and the oleeranon process to elicit TineFs sign. The elbow flexion test is another provocative test for ulnar nerve compression at the elbow. To perform the elbow flexion test, the examiner passively flexes the patients elbow to the maximal degree possible and holds it in this position for a minutę or morę (Fig. 3-44). In the presence of cubital tunnel syndrome, the patient often reports the gradual development of paresthesias in the smali finger and the ring finger. These symptoms may be further accentuated by applying digital pressure directly over the ulnar nerve as it runs through the cubital tunnel. This combination of prolonged passive

Figurę 3-41. A and B, Sensory distribution of the median nerve in the hand.