The author recalls the phenomena which control bronchomotility, without a personal study but based on recent bibliography. After recalling the bronchial nerve supply, the chemical intermediates, the various responses of the bronchial tree to autacoids, the author recalls the association of anesthesia and bronchospasm. Although the bronchial reactions of histaminic origin are the most frequent, mechanical or chemical irritation is recalled with an elementary description of "irritant receptors" and stretch receptors. Finally, the other causes of bronchial narrowing are considered: vago-sympathetic imbalance, atopic background, influence of the anesthetic on vagal tone or on adrenal medullary secretion.