The relative elongation with elbow flexion of the ulnar nerve, proxima
l and distal to the cubital tunnel, and of the cubital tunnel retinacu
lum, was measured in cadaver specimens by stereophotogrammetry. The pr
oximal part of the ulnar nerve elongated significantly with full elbow
flexion. No significant change of length was measured in the distal p
art of the nerve. The length of the cubital tunnel retinaculum increas
ed by an average of 45% from full elbow extension to full flexion.