In high lesions of ulnar nerve like elbow fractures or dislocations the degree of clawing is markedly less than in low ulnar lesions this is called ULNAR PARADOX and is due to:
Ans. A. The fact that ulnar half of FDP is paralyzed and hence there is no flexion at the IP joints.Claw hand basically is because of paralysis of the lumbricals whose action is flexion at the MCP joint and extension at the IP joints. A claw hand is extended at the MCP and flexed at the IP because of unopposed action of the long flexors, since in the High ulnar lesion the long flexor is paralyses, there is less clawing.
The fact that the ulnar half of the FDP is paralyzed and hence there is no flexion at the IP joints.
The lumbricalis are spared and hence there is no clawing
The Median nerve compensates for the ulnar nerve
The interossei increase their tone and extend the IP joint
Peripheral Nerve Injuries