Blood flow in arm and finger during muscle contraction and joint position changes

¹ Research Laboratories, University of California, Santa Barbara; and Department of Physiology, University of Southern California Medical School, Los Angeles, California

Digital pulse and blood flow were measured while subjects squeezed a hand dynamom eter. The pulse wave was obliterated at 25% maximum hand grip, and blood flow was occluded at 45% maximum hand grip. Maximum hand grip did not reduce radial pulse, therefore occlusion occurred at some point distal to the forearm muscles. Changes in blood flow suggest that the superficial palmar arch is occluded first and subsequently the deep palmar arch is arrested. Strong contraction of the biceps abolished the radial pulse, but did not diminish the brachial pulse wave; therefore occlusion must occur between the upper arm and the wrist, probably immediately distal to the elbow where the artery proceeds under the fascia of the biceps. Contracting the pronator teres also obliterated the digital pulse wave. Finally, it is possible to eliminate the digital pulse by rotating the clavicle backward, pressing the artery against the first rib. This was accomplished by horizontal retraction of the upper arm while it was elevated laterally or by simply jamming back the forward and horizontally elevated extremity.