Somatosensory System for Balance

Balance is maintained by integrating three sensory systems: the somatosensory, the vestibular (see vestibular-system), and the visual (see visual-system-balance). The somatosensory system supplies information about the body's position relative to itself and to the support surface.

Its inputs are:

• Proprioception (joint-position sense and kinesthesia) from muscle spindles, Golgi tendon organs, and joint receptors (see proprioception).
• Cutaneous and plantar pressure receptors, especially on the soles of the feet, signaling how body weight is distributed across the base of support and detecting sway and surface texture/slope.

On a firm, stable surface in good light, the somatosensory system is normally the dominant contributor to standing balance. When the support surface becomes unstable or compliant (foam, balance pad, BOSU), somatosensory information becomes unreliable, and the system must lean more on vestibular and visual input — a shift called sensory reweighting (see sensory-reweighting). Training deliberately manipulates surface stability and foot input (e.g., barefoot work, unstable surfaces) to challenge and improve somatosensory contribution.

• One of three balance senses (somatosensory, vestibular, visual).
• Inputs: proprioception (muscle/tendon/joint receptors) + cutaneous/plantar pressure receptors.
• Normally dominant for standing balance on firm surfaces in good light.
• Made unreliable by compliant/unstable surfaces, forcing reliance on the other two systems (sensory reweighting).

• proprioception — the system's core input.
• vestibular-system, visual-system-balance — the other two balance senses.
• sensory-reweighting — how the systems shift dominance with conditions.
• unstable-surface-training — exploits unreliable somatosensory input.