Define the vestibulo-spinal reflex and explain its contribution to postural control.

• A. VSR uses vestibular input to coordinate neck, trunk, and limb muscles to maintain balance during movement or perturbations
• B. VSR primarily stabilizes gaze via vestibulo-ocular pathways
• C. VSR relies on olfactory cues to maintain posture
• D. VSR is only active during quiet standing

Answer: (A)

The vestibulo-spinal reflex is about using head-motion signals from the vestibular system to automatically adjust the tone and activity of muscles throughout the neck, trunk, and limbs so the body stays upright and balanced when you move or when the ground tilts or you’re perturbed. Signals come from the vestibular organs in the inner ear and travel to the brainstem, where they are relayed through the vestibulospinal tracts to spinal motor circuits that control posture. The medial tract mainly influences the head and upper trunk, while the lateral tract helps modulate extensor muscles in the legs to keep the center of gravity over the base of support. This reflex provides rapid, involuntary corrections that support postural control during movement and sudden perturbations, working alongside vision and proprioception.

Stabilizing gaze via the vestibulo-ocular system is a separate function, not the vestibulo-spinal one. Olfactory cues don’t play a role in this reflex, and it isn’t limited to quiet standing—it activates whenever balance needs to be maintained during motion or disturbance.