VOICE AND SPEECH. 863 



The ventricular bands are parallel with and just above the true vocal cords, 

 from which they are separated by a narrow slit. They do not, however, reach 

 so near the middle line as the true cords, which can be seen between and below 

 the bands. The ventricular bands project more or less into the cavity of the 

 larynx like overhanging lips, so that each band forms the inner wall of a 

 space closed by the true vocal cords below, and communicating with the cavity 

 of the larynx through the narrow slit above mentioned. The spaces thus 

 bounded internally by the false cords are known as 



The Ventricles of Morgagni (Fig. 295). No complete explanation has been 

 offered as to the purposes served by the ventricles of Morgagni and the false 

 vocal cords. Numerous mucous and serous glands seated in the ventricular 

 bands pour their secretions into the ventricles, whence the fluid may be trans- 

 mitted by the overhanging lips of the ventricular bands to the true vocal 

 cords ; hence, an important function of the former structure, probably, is to 

 supply to the vocal cords the moisture necessary to their normal action. The 

 secretion contained within the ventricle is protected by the ventricular band 

 from the desiccating influence of the passing air-currents. The existence of 

 the ventricular spaces also permits free upward vibration of the true cords. 

 The ventricles of Morgagni in some of the lower animals, as the higher apes, 

 communicate with extensive cavities which serve an obvious purpose as reso- 

 nating chambers for the voice, and perhaps the preservation of this function in 

 the ventricles themselves is still of importance in the human being. It is not 

 improbable that the ventricular bands find their most important function as 

 sphincters of the larynx, the superior opening of which may be firmly occluded 

 by their approximation. The well-known fact that during strong muscular 

 effort the breath is held from escaping is, according to Brunton and Cash,' 

 due to the meeting of the false cords in the middle line. The overhanging 

 shape of the cords allows them to be readily separated by an inspiratory blast, 

 but causes them to be more firmly approximated by an expiratory effort. This 

 mechanism recalls the mode of action of the semilunar valves of the heart. 



The true vocal cords arise from the angle formed by the sides of the thyroid 

 cartilage where they meet in front, a little below its middle point, and, passing 

 backward, are inserted into the vocal processes of the arytenoid cartilages. 

 The aperture between the vocal cords and between the vocal processes of the 

 arytenoids is known as the glottis or rima glottidis (Figs. 301, 302). Since, as 

 will be seen later, the vocal cords may be brought together while the vocal pro- 

 cesses of the arytenoids are widely separated at their bases, the space between 

 the cords themselves is sometimes called the rima vocalis and that between the 

 vocal processes the rima respiratoria. 



In the adult male the vocal cords measure about 15 millimeters in length 

 and the vocal processes measure 8 millimeters in addition. In the female the 

 cords are from 10 to 11 millimeters in length. The free edges of the cord are 

 thin and straight and are directed upward ; their median surfaces are flattened. 

 Each cord is composed of a dense bundle of fibres of yellow elastic tissue, 

 1 Brunton and Cash : Journ. Anal, and Phys., 1883, vol. xvii. 



