624 



THE VALVULAE ACTION OF THE LARYNX. 



In conjunction with THEODOEE CASH, M.D. 



(Reprinted from the Journal of Anatomy and Physiology, vol. xrii, 1882-1883.) 



Closure of the glottis plays a most important part in all expul- 

 sive acts, such as coughing, sneezing, vomiting, or defsecation 

 or in those muscular actions where it is necessary to have the 

 thorax fixed, in order to enable the muscles attached to it to act 

 with greater advantage or greater precision. On looking at the 

 human larynx, it not unfrequently happens that the mere act 

 of introducing the mirror into the fauces excites movements of 

 retching. The appearance which the larynx then presents, is 

 that of a somewhat circular or slightly elliptical opening com- 

 pletely filled by three bulging segments, strongly reminding one 

 of the appearance of the aortic valves, as seen from below in an 

 injected aorta. On consulting several text-books on physiology 

 we find that the mode of closure of the glottis is treated in a 

 very cursory way. In the wonderfully complete physiology of 

 Haller we can find no definite information, nor is there any in 

 Todd's Cyclopcedia of Anatomy and Physiology. In MuUer's 

 Physiology, translated by Dr. Baly, 2nd edition,* we find the 

 statement that in holding the breath the air tubes are cut off 

 from the mouth and nostrils by approximating the posterior 

 palatine arches, and pressing the root of the tongue against the 

 palate. In Carpenter's Physiology, 9th edition, and in Foster's 

 Physiology, 3rd edition, we have also failed to find a definite 

 account of the mechanism of the closure of the glottis. In 

 Czermak's. Treatise on the Laryngoscope,^ he states that during 

 closure of the glottis he has observed that — 



"(1) The arytenoid cartilages intimately meet at their in- 

 ternal surfaces and processes, and they bring the edges of the 

 vocal cords in contact ; (2) the superior vocal cords approach 



» Vol. i, p. 360. 



t New Sydenham Society publications, toI. xi, 1861. 



