Bony Characteristics Determine the Behaviour of the Interosseous Membrane (IOM) During Supination, Neutral Position, and Pronation of the Forearm

Abstract

To analyse the behaviour of the forearm interosseous membrane (IOM) in vitro, forearm anatomical specimens supple enough to simulate in vivo movements, were observed in supination, neutral position, and pronation. The bony, so-called interosseous borders of radius and ulna lie in frontal plane in supination. Their distal halves partly follow each other’s curvatures, leaving the IOM in-between undulated and rather lax. The neutral or “handshake” position, ulna unchanged while the radius’ arched curvature lies in sagittal plane, creates largest distances between the bones, causing the IOM to be maximally taut. In full pronation (radius and ulna crossed) the interosseous borders re-approach each other, causing the IOM to become undulated and lax again. These bony characteristics, directed differently dependent of forearm position, causing the IOM to be whether lax or taut, may generate different proprioceptive signals in vivo, e.g. in handling vertical PC mice.