Claw hand is caused by damage to?

Ans. a (Ulnar nerve). (Ref. Maheshwari, Orthopaedics, 2nd ed., 51)# Claw hand means hyperextension at metacarpophalangeal joints & flexion at the proximal & distal interphalangeal joints. This occurs due to paralysis of the lumbricals, which flex the metacarpo-phalangeal joint & extends the interphalangeal joints.# Paradoxically clawing is more marked in lower ulnar nerve palsy than in high due to the latter, flexor of the fingers (both the finger flexors) are also paralysed.# In ulnar nerve palsy only the medial 2 fingers develop clawing while all 4 fingers develops clawing in combined median & ulnar nerve palsies. NerveMuscle groupFunctional deficit or sign1.Long thoracicSerratus anteriorWinging scapula2.SuprsascapularInfraspinatus, SupraspinatusDifficulty in initiating arm abduction3.AxillaryDeltoid and teres minorInability to fully abduct arm4. Extensors of forearms, wrist proximal phalangesLoss of arm extension, loss of forearms extension, supination, es. and thumb abduction, loss of wrist extension (wrist drop), loss of proximal phalangeal extension and thumb extension.Saturday night palsy5.MusculocutaneousFlexors of arm and forearmWeak arm and forearm flexion,weak forearm supination.6.MedianWrist and hand flexors thenar muscles,Paralysis of flexor, pronator, and inability to fully flex the index and middle fingers, (sign of benediction), "pointing index finger", labourer's nerve7.UlnarWrist and hand flexorsInability to extend the distal and middle phalanges (clawhand); loss of thumb abduction, froment sign positiveTardy ulnar palsy- cubitus valgus.