Median nerve palsy

Question 1

Mechanism of median nerve palsy

Answer 1

Elbow: dislocation of forearm
Fracture of wrist
Carpal tunnel syndrome

Question 2

Clinical sign of median nerve palsy

Answer 2

High lesion (Hand of Benediction):
- ACTIVE test
- ask the patient to flex their fingers –> see only 4-5th fingers can flex (flexor digitorum profundus by ulnar nerve); cannot flex thumb (flexor pollicus); 2-3th fingers (flexor digitorum profundus by median nerve)

Low lesion (Ape hand):
- RESTING position
- flattening of thenar eminence
- loss of thumb palmar abd and opposition

Question 3

Functional deficit

Answer 3

• loss of palmar abduction, opposition

Question 4

Innervation of median nerve

Answer 4

pronator teres, flexor carpi radialis and palmaris longus

flexor digitorum superficialis

flexor pollicis longus, pronator quadratus, and the lateral half of the flexor digitorum profundus by Anterior Interosseous Nerve

Question 5

Clinical sign of anterior interosseous nerve

Answer 5

Ballentine’s sign = unable to make a “OK” sign
AIN innervate Flexor pollicis longus (thumb IPJ), Lateral half of flexor digitorum profundus (flex 2-3th digit DIPJ), Pronator quadratus

Question 6

Special test for median nerve injury

Answer 6

Phalen’s test (wrist flexion 60sec max.)
Tinel’s sign (tapping over transverse carpal ligament)

Feel pain/anesthesia/paresthesia

Question 7

SSx of Carpal tunnel syndrome

Answer 7

Paresthesias to the distribution of the distal median nerve (palmar aspect of thumb, IF, MF, radial half of RF)

Thenar atrophy

loss of sensibility (2-point discrimination)