902 



THE ORGANS OF VOICE 



separated behind. They inchide ])etween them an angle varying from 80° to 90°, and 

 are somewhat obhquely inehned, their outer surfaces looking slightly downwards as 

 well as outwards. Eaeh plate has an outer and an inner surface and four borders. 

 The upper and lower posterior angles of each plate project upwards and down- 

 wards to form its superior and inferior cornua. 



The outer surface is smooth, and is crossed by an oblique and often very faintly 

 defined line, or by an occasional filirous band. This is marked at each extremity 

 by a small tu])ercle. These tubercles are more pronounced in old subjects. The 

 line and the adjacent cartilage give attachments to the thyro-hyoid and sterno- 

 thyroid muscles, and thi^ inferior constrictor which overlaps the smaller portion of 

 the ala lying behind the line. 



The inner surface is also smooth ; it is concave, and in contact with the mucous 

 membrane which lines the sinus pyriformis, with branches of the laryngeal nerves and 

 vessels, and with the external thyro-ar3'tenoid and lateral crico-arytenoid muscles. 



Fig. 523. — Front View of the Cartilages of the Lakvxx. 



Bourgerv and Jacob.] 



BODY OF HYOIO BONE 

 Thyro-hyoid ligament 



Cartilago triticea 

 Foramen for superior 

 laryngeal nerve 

 Median portion of thyro- 

 hyoid membrane 

 SUPERIOR CORNU OF THYROID 

 CARTIUGE 



MEDIAN NOTCH OF THYROID 

 CARTILAGE 



Fomum Adami 



(Modified from 



OBLIQUE LINE OF THYROID 

 CARTILAGE 



Crieo-thyroid membrane 



INFERIOR CORNU OF THYROID 

 CARTILAGE 



THIRD RING OF TRACHEA 



OBLIQUE LINE BELOW SUPERIOR 



TUBERCLE 

 WING OF CARTILAGE BEHIND 



OBLIQUE LINE 



OBLIQUE LINE ABOVE INTERIOR 



TUBERCLE 



ANTERIOR BORDER OF INFERIOR 

 CORNU 



The anterior or isthmic border, which is also the shortest, corresponds to the 

 junction of the two al;r in the median line in front; very prominent above, where 

 it forms the pomum Adami, it becomes depressed before again ])rojecting less 

 markedly l^elow. Posteriorly, at the angle of junction it gives attachment to the 

 stalk of the epiglottis, tlie true and false vocal cords, the thyro-arytenoid and thyro- 

 epiglottidei muscles. 



The superior border, which gives attachment to the thyro-hyoid membrane, is 

 sinuous. Slightly dc] tressed posteriorly, it rises in front, and then becomes abruptly 

 scooped out and everted to form tlie side of the great median notch. 



The inferior border is somewhat sinuous. It gives attachment in front to the 

 middle portion of the crico-thyroid membrane, and Ix-hind to tlie crico-thyi-oid 

 muscle, and presents the small tubercle already noticed at the termination of the 

 oV)lique line. 



