The Postural Tonic System
Human movement is organized by the Central Nervous System (CNS), which plans, oversees, and executes voluntary, automatic, and reflex movements.
The execution of a movement results from the collaboration between the Dynamic System and the Tonic-Postural System (TPS), which initiate, guide, and conclude the movement.
The proper refinement of incoming sensory signals and the hierarchical optimization of motor systems lead to a stable upright posture and to motor tasks characterized by fluid, efficient, and coordinated movements.
Ensures the maintenance of stability;
Generates appropriate postural anticipations;
Enables motor responses that are coordinated and aligned with the objective;
Promotes movement efficiency for greater energy conservation.
The sensory systems that interact most significantly in the control of posture are:
VESTIBULAR
VISUAL
SOMATOSENSORY PROPRIOCEPTIVE
The central nervous system (CNS) weighs this information based on its reliability and partially or entirely disregards it.
At this level, proprioception plays a primary role because it is “the sense that gives coherence to the other senses”; when functioning efficiently, it relieves the visual and vestibular systems of postural control duties, allowing them to intervene only when necessary to perform their functions optimally.
The vestibular system acts as an emergency system that must intervene when the head is subjected to movements of a specific amplitude and speed.
The visual system can perform its orienting function when it is freed from the task of visual fixation for postural control.