Mechanisms of limb stability:

• Antagonist muscle architecture produces an equilibrium point. Polit and Bizzi experiments with de-afferented monkeys showed passive properties can reach target, but cannot resist pertubation very well.
• Passive, spring-like properties of limb promotes stability.
• CNS reflexes.
• Neuropathy - cannot sense location of limbs without vision.
• [Mussa-Ivaldi] shows stiffness of the arm remains roughly constant when expressed in terms of joint coordinates.