THE RELATIONSHIP OF THE INTEROSSEOUS MEMBRANE TO THE AXIS OF ROTATIONOF THE FOREARM

Fresh anatomic specimen forearms were studied using a mechanical devic e, the axis finder, to locate the axis of rotation. The relationship o f the axis to the membrane was demonstrated directly using a small jig . The axis of rotation of the forearm is constant and independent of e lbow flexion or extension. It runs from the center of the radial head to the center of the distal ulna. All fibers of the interosseous membr ane cross the axis of rotation near their distal insertion into bone. This relationship of the ligaments to the axis of rotation is similar to those of the ankle, knee, and thumb joints. The membrane does not l imit forearm rotation and can provide little stability if the bony rin g is disrupted.