Dr. Ebraheim’s educational animated video describes the positions of the hand and fingers associated with injury to the ulnar and median nerves.
The position of the hand can determine what kind of nerve injury thet patient may have.
Ulnar nerve injury:
1claw hand
2Wartenberg's sign
3cannot cross the fingers
injury to the ulnar nerve may produce a ‘claw hand’ deformity. The deformity usually occurs if the injury to the ulnar nerve is below the elbow. Flexion of the fingers occurs due to a functional profundus muscle for the 4th and 5th fingers. Wartenberg’s sign is due to a low ulnar nerve injury and consists of abduction of the 5th finger caused by unopposed ulnar insertion of the extensor digiti quinti. As a result of ulnar nerve injury the patient is unable to cross or abduct the fingers. Adduction of the fingers come from the palmar interossei (PAD). Abduction of the fingers come from the dorsal interossei (DAB).
The Forment’s test is used to test for palsy of the ulnar nerve which may occur with entrapment of the ulnar nerve within the cubital tunnel (cubital tunnel syndrome). When pinching a piece of paper between the thumb and index finger, the thumb IP joint will flex if the adductor pollicis muscle is weak due to ulnar nerve palsy.
Median nerve injury:
1hand of benediction
2cannot do the OK sign.
Prolonged compression or injury of the median nerve at this level may result in the “hand of benediction” . the ability to flex the 2nd and possibly the 3rd digits is lost due to loss of innervation of the lateral two lumbricals of the hand. The hand of benediction is different from an “ulnar claw hand”. Ulnar claw hand refers to damage to the ulnar nerve and is seen when attempting to extend all the digits (leaving the 4th and 5th digits flexed).
The O.K sign is used to check for paralysis of the anterior interosseous nerve due to entrapment or compression injury. Patient with paralysis of the anterior interosseous nerve will be unable to make the O.K sign. typical pinch attitude associated with anterior interosseous nerve injury.
Radial nerve injury:
1wrist drop
2cannot do the hitch hike sign
3will be able to extend wrist but unable to extend fingers
injury to the radial nerve will cause wrist drop. High radial nerve injuries usually occur due to fractures of the distal third of the humeral shaft. The fracture may cause injury to the radial nerve which results in paralysis of the wrist and finger extensors. The patient will be unable to perform the “hitch hike” sign of finger extension. Low radial nerve injury usually occurs around the elbow affecting the finger and thumb extension. If the patient does not have wrist drop, and still cannot perform the “hitch hike” sign, check the patient for posterior interosseous nerve injury. Patient with posterior interosseous nerve injury can perform wrist extension, but no finger extension. Recovery of the wrist extensors, but finger externsors are not yet recovered is a sign of posterior interosseous nerve injury that is not recovered yet. With the wrist placed in extension, the patient cannot extend the finger= posterior interosseous nerve injury.

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Background music provided as a free download from YouTube Audio Library.
Song Title: Every Step