When a subject sitting upright turns the head to the right, the vestibulo-ocular reflex generates compensatory eye movements. The correct sequence is:

• A Right horizontal canal afferents are excited, and both eyes move slowly to the left ✓
• B Left horizontal canal afferents are excited, and both eyes move slowly to the right
• C Right horizontal canal afferents are inhibited, and both eyes move slowly to the right
• D Both canals are equally excited, and the eyes remain stationary

Explanation

Rightward head rotation deflects the right horizontal canal cupula towards the utricle (ampullopetal flow), which is excitatory for that canal, while the left canal is inhibited. Vestibular nuclei drive contralateral abducens neurons, producing a slow conjugate eye movement to the left that stabilises gaze on the target. Fast-phase nystagmus then resets the eyes to the right, giving right-beating nystagmus.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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