Hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints is caused by injury in the

i.e. (Ulnar nerve): (59, 134-BDC-l 5th)An ulnar nerve lesion at the writ produces ulnar claw hand'CLAW HAND - due to the un opposed action of the long flexors and extension of the fingers, there is hyperextension at the metacarpo phalangeal joint and flexion at the interphalangeal joints involving the ring and little fingers - more than the index and middle fingers* If both median and ulnar nerves are paralysed the result is complete claw hand* Ulnar injury at the wrist can be tested by froment's sign