Does an ulnar nerve lesion influence the motion of the index finger?

Clawing of the ring and little fingers and "rolling" during prehension grip are well-known clinical phenomena of ulnar nerve lesions. In contrast to this the index and middle fingers seem to move normally. We compared the movement of right index fingers in healthy people with the right index fingers of people with an ulnar nerve lesion. The movement was measured using a three-dimensional real time motion analysis system based on ultrasound. The angles of the joints were plotted in a rectangular coordinate system. Statistical analysis of the numerical data showed no difference between the two groups. We trained a neural-network (Learning Vector Quantization) with the data of both groups. The network was able to distinguish between people with and without lesions of the ulnar nerve. We conclude that prehension grip of the index finger is also influenced by paralysis of the ulnar nerve.