Claw hand is caused by:

(Ulnar nerve) Ref: 174-BDC-l, 242, 342-Appley* The most common are drop wrist and drop fingers - Radial nerve palsy* Siamian thumb and pointing index finger - Median nerve palsy* Partial cloud hand -- ulnar nerve palsy* Complete claw hand - ulnar and median nerve palsyUlnar nerve lesions(A) Low ulnar nerve palsy: Intrinsic muscle wasting, in the ring and little fingers in the knuckle joints are hyperextended (paralysed lumbricals) and the interphalangeal joints are flexed (paralysed interossei)(B) High ulnar nerve palsv: Profundus action is lost so the terminal interphalangeal joints are not flexed (ulnar paradox)Fromet's sign - Finger abduction is weak and this together with loss of thumb adduction, makes pinch difficult. The patient is asked to grip a sheet of paper forcefully between thumb and index fingers. While the examiners tries to pull it away: powerful flexion of the thumb interphalangeal joint signals weakness of adductor pollicis and over compensation by the flexor pollicis longus.