200 SPECIAL PHYSIOLOGY. 



production of vocal sounds as exponents of the feelings, emotions, and desires. 

 Speech is a further prerogative of man. 



VOICE AND SPEECH. 



The Organ of Voice. 



The special organ of voice in man, is that portion of the air-pas- 

 sages called the larynx, a sort of hollow chamber, which extends from 

 near the root of the tongue to the first ring of the trachea. 



The larynx, Fig. 9, 'I, is placed in the middle line of the neck, 

 where it forms a considerable projection, larger above than below ; it 

 is suspended from the hyoid bone, h, by muscles and ligaments ; its 

 cavity communicates with the pharynx, p, above, and with the trachea, 

 b, below. Although the larynx is the proper organ of voice, yet the 

 lungs and the movable and moving parts of the thorax, serve to pro- 

 pel the necessary air through this organ ; whilst the air-passages and 

 cavities above it, including the pharynx, mouth, and nasal cavities, 

 assist in modifying the vocal sounds, and are therefore adjuvant and 

 supplementary organs of voice. 



The framework of the larynx is made up of cartilages, which are 

 connected together by ligaments, and furnished with muscles, extrinsic 

 and intrinsic ; the whole organ is of course supplied with bloodvessels, 

 nerves, and lymphatics ; its interior is lined by a highly sensitive 

 mucous membrane. 



The cartilages, which constitute the basis of the organ, are four in 

 number; viz., the cricoid, thyroid, and the two aryterioid. The 

 cricoid, Fig. 55, a, b, 5, Fig. 56, B, 5,*which resembles a signet-ring 

 placed vertically, with its broader portion turned backwards, forms 

 the base or lower part of the organ. On the summit of the posterior 

 border of the cricoid, are the two arytenoid cartilages, one on each side, 

 Figs. 55, 56 * ; these are two small pyramidal pieces situated close to 

 each other, and connected with the cricoid cartilage by means of true 

 ball and socket joints. Each presents at its base, an anterior and a 

 lateral process. As we shall hereafter see, they are most important 

 structures in the production of the voice. The thyroid cartilage, 2, 2, 

 rests upon the fore part of the cricoid ; it is the largest cartilage in 

 the larynx, covering the others in front and at the sides. It consists 

 of a broad, cartilaginous plate, forming two wings or alae, united at 

 an acute angle in the middle line in front, where it forms the projec- 

 tion called the pomum Adami, or Adams apple, Fig. 9 ; its right and 

 left hinder borders terminate, above and below, in little processes ; of 

 these, the two upper ones, called the superior cornua, serve to connect 

 the cartilage, by means of ligaments, with the hyoid bone ; and the 

 two lower ones, called the inferior cornua, present each a small, 

 smooth, oval surface for articulation with the cricoid cartilage. The 

 cartilages of the larynx are composed of pure cartilage ; in advanced 

 age, they frequently undergo partial ossification. 



Behind the tongue, and in front of the upper opening of the larynx, 

 is a curved, upright, fibro-cartilaginous plate, named the epiglottis, 



