ABSTRACT
A body configuration is the spatial form of the body and its parts (standing at ease, doubled over, sitting, lying down), while the configuration system is the collection of networks which holds and adjusts configurations. The configuration system is subserved by the gamma motor neurons and stretch reflex circuitry. Adjustments to the configuration are movements, and both the static and dynamic properties of a movement are regulated during its orchestration. The thrust system accelerates and decelerates body parts during a movement and therefore regulates the velocity of each part along its trajectory. The stretch reflex must be regulated during a movement so as not to oppose it, and hence coactivation of alpha and gamma neurons is implicated for thrust control.
