The flared nostrils offer a deceptive picture: at a gallop, a horse seems to be running with one airway shut. Yet the arrangement is not a handicap. A strict biological bargain. The soft palate seals the oral route, while the larynx and nasal passages form a conduit from nostril to lung. During exertion, muscles flare the nostrils, enlarging the entry before air meets the long nasal channel.That b...More