TRACHEA AND BRONCHIAL TUBES. 359 



The muscles which are engaged in producing these move- 

 ments are animated by the inferior laryngeal branches of 

 the pneumogastric nerves. If these nerves be divided, the 

 movements of the glottis are arrested, and respiration is 

 very seriously interfered with. This is particularly marked 

 in young animals, in which the walls of the larynx are com- 

 paratively yielding, when the operation is frequently followed 

 by immediate death from suffocation. The movements of 

 the glottis enable us to understand how foreign bodies of 

 considerable size are sometimes accidentally introduced into 

 the air-passages. 



The respiratory movements of the larynx are entirely dis- 

 tinct from those engaged in the production of the voice, and 

 are simply for the purpose of facilitating the entrance of air 

 in inspiration. 



Attached to the anterior portion of the larynx is the epi- 

 glottis ; a little leaf-shaped lamella of fibro-cartilage, which, 

 during ordinary respiration, projects upward, and lies against 

 the posterior portion of the tongue. During the act of de- 

 glutition, respiration is momentarily interrupted, and the air- 

 passages are protected by the tongue, which presses backward 

 carrying the epiglottis before it, completely closing the open- 

 ing of the larynx. Physiologists have questioned whether 

 the epiglottis be necessary for the complete protection of the 

 air-passages ; and, repeating the experiments of Magendie, it 

 has been frequently removed from the lower animals without 

 apparently interfering with the proper deglutition of solids 

 or liquids. We have been satisfied from actual experiment 

 that a dog will swallow liquids and solids immediately after 

 the ablation of the epiglottis, without allowing any to pass 

 into the trachea ; but it becomes a question whether this ex- 

 periment can be absolutely applied to the human subject. 

 In a case of entire loss of the epiglottis, which was observed 

 in the Bellevue Hospital, the patient experienced slight 

 difficulty in swallowing, from the passage of little parti- 

 cles into the larynx, which produced cough. This case 



