Arterial dominance in the hand.

Arterial pressure was measured simultaneously in the thumb and in the contralateral arm using strain-gauge plethysmography in 100 healthy persons aged 13--43 yr, before and after compression of the radial or the ulnar artery. The radial and ulnar pulses were palpable in all instances. In 29 (14.5%) hands compression of either artery did not reduce the thumb pressure. In 152 (76%) occlusion of the radial artery caused a decrease of more than 10 mm Hg, but never to less than 40 mm Hg. In 91 (45.5%) occlusion of the ulnar artery reduced thumb pressure, on three occasions to less than 40 mm Hg. Radial dominance was shown in 110 hands (55.0%), 24 (12.0%) showed ulnar dominance and in 66 (33.0%) neither vessel dominated.