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.