the Physiology of the Human Voice. 205 



its laryngeal surface, are found numerous minute orifices in 

 which glands lie imbedded. The epiglottis is repressed by 

 two pair of small muscles called the Aryieno-Epiglottidei, and 

 the Thyro-Epiglottidei. The effect arising from the depres- 

 sion of the epiglottis u|)on the fundamental key of the vocal 

 tube is somewhat uncertain. Majendie and Mayo * have in- 

 ferred from the experiments of M. Grenie f that the epiglottis 

 prevents the tones of the voice from becoming more acute 

 when they increase in intensity; this hypothesis is however de- 

 cidedly erroneous I, in as much as neither the elevation nor de- 

 pression of the epiglottis can affect or regulate the vibrations of 

 the glottis. 



The Thyro- Arytenoid ligaments%, or chordae vocales, as they 

 are commonly (though improperly) denominated, are com- 

 posed of fasciculi of parallel fibres arising from the bases of the 

 arytenoid cartilages ; thence proceeding forwards and inwards, 

 they meet, and are inserted together into the posterior surface 

 of the thyroid cartilage at the junction of its alae. 



These ligaments are immediately after death almost trans- 

 parent, and nearly inelastic. These characters, however, very 

 soon disappear by exposure to the air, and they become opake, 

 and yielding. Their length on an average, in the adult male, 

 is six lines, and in the female four and a half lines. 



The chink formed by the separation of these ligaments is the 

 Rimula Glottidis. The form of this chink in a state of relax- 

 ation is elliptical, but when the cartilages are widely separated 

 it assumes the form of an isosceles triangle. The breadth of 

 the chink when relaxed is about three lines. The movements 

 of the larynx are effected by two sets of muscles ; the one at- 

 tached principally to the os hyoides, which is the centre of mo- 

 tion of all these parts and serves to raise and depress the vocal 

 tube ; the other is destined to control the movements of the 



* Vide Mayo, Physiol., p. 334. 



•f " M. Grenie a trouve qu'on pouvait corriger ce defaut en mettant au- 

 dessus des anches, dans le tuyau vocal, des petites lamelles de papier, fixes 

 seulement par leur base, et qui, s'elevant quand le courant s'accelere, s'abais* 

 sant quand il se ralentit, peuvent, par ces positions diverses, modifier les on- 

 dulations de nianiere que le ton reste constant, avec une intensite de son 

 differcnte." — Precis Elementaire dc Physique Expirimentale, par J. Biot, 

 page 399. 



J According to Liscovius (p. 34.), neither its depression, its elevation, nor 

 even its entire removal have any effect on the voice. Haller (loc. cit. EI. 

 Physio, lib. ix. p. 5/2,) appears also to be of the same opinion : " Epiglottis 

 cquidcm nihil faciat ad vocem ; cum ea (vox) nata sit ct perfecta quam 

 primum aer ex glottidis rinia prodiit ct absque epiglottide aves suavissimc 

 canant." 



$ Fig. 2. 



