<prompt> Cough reflex on scratching the floor of external auditory meatus is due to which nerve?Auricular branch of vagusAuriculo temporalGreater auricular nerveFacial nerve  <response>: Nerve Supply of External acoustic meatus Anterior wall and roof by auriculotemporal nerve Posterior wall and floor by auricular branch of vagus nerve Arnold N Posterior wall of auditory canal also receives innervations by facial nerve through auricular branch of vagus Cough reflex is dt internal laryngeal N. Coughs reflex during syringing is dt Arnolds Nerve 