



THE LARYXX 1073 



orepart of the neck, where it presents a considerable projection in the middle 

 line. It forms the lower part of the anterior wall of the pharynx, and is covered 

 behind by the mucous lining of that cavity; on either side of it lie the great vessels 

 of the neck. Its vertical extent corresponds to the fourth, fifth, and sixth cervical 

 vertebrae, but it is placed somewhat higher in the female and also during childhood. 

 Symington found that in infants between six and twelve months of age the tip 

 of the epiglottis was a little above the level of the fibrocartilage between the 

 odontoid process and body of the axis, and that between infancy and adult life 

 the larynx descends for a distance equal to two vertebral bodies and two inter- 

 vertebral fibrocartilages. According to Sappey the average measurements of the 

 adult larynx are as follows: 



In males. In females. 



Length 44 mm. 36 mm. 



Transverse diameter .... 43 " 41 " 



Antero-posterior diameter ... 36 26 



Circumference 136 " 112 " 



Until puberty the larynx of the male differs little in size from that of the female. In the 

 female its increase after puberty is only slight; in the male it undergoes considerable increase; 

 all the cartilages are enlarged and the thyroid cartilage becomes prominent in the middle line of 

 the neck, while the length of the rima glottidis is nearly doubled. 



The larynx is broad above, where it presents the form of a triangular box flattened 

 behind and at the sides, and bounded in front by a prominent vertical ridge. 

 Below, it is narrow and cylindrical. It is composed of cartilages, which are con- 

 nected together by ligaments and moved by numerous muscles. It is lined by 

 mucous membrane continuous above with that of the pharynx and below with 

 that of the trachea. 



The Cartilages of the Larynx (cartilagines laryngis) (Fig. 950) are nine in number, 

 three single and three paired, as follows: 



Thyroid. Two Corniculate. 



Cricoid. Two Cuneiform. 



Two Arytenoid. Epiglottis. 



The Thyroid Cartilage (cartilago thyreoidea) is the largest cartilage of the larynx. 

 It consists of two laminae the anterior borders of which are fused with each other 

 at an acute angle in the middle line of the neck, and form a subcutaneous projec- 

 tion named the laryngeal prominence (pomum Adami). This prominence is most 

 distinct at its upper part, and is larger in the male than in the female. Immediately 

 above it the laminae are separated by a V-shaped notch, the superior thyroid notch. 

 The laminae are irregularly quadrilateral in shape, and their posterior angles are 

 prolonged into processes termed the superior and inferior cornua. 



The outer surface of each lamina presents an oblique line which runs downward 

 and forward from the superior thyroid tubercle situated near the root of the 

 superior cornu, to the inferior thyroid tubercle on the lower border. This line 

 gives attachment to the Sternothyreoideus, Thyreohyoideus, and Constrictor 

 pharyngis inferior. 



The inner surf ace is smooth; above and behind, it is slightly concave and covered 

 by mucous membrane. In front, in the angle formed by the junction of the laminae, 

 are attached the stem of the epiglottis, the ventricular and vocal ligaments, the 

 Thyreoarytaenoidei, Thyreoepiglottici and Vocales muscles, and the thyroepiglottic 

 ligament. 



The upper border is concave behind and convex in front; it gives attachment to 

 the corresponding half of the hyothyroid membrane. 



The lower border is concave behind, and nearly straight in front, the two parts 

 being separated by the inferior thyroid tubercle. A small part of it in and near 

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