i8l8 



HUMAN ANATOMY. 



The inferior thyro-arytenoid ligaments (ligamenta vocalia) are a pair of 

 bands of fibrous tissue, chiefly elastic, supporting the free edges of the true vocal 

 cords, extending from the angle of the thyroid a little below the false ones to the 

 vocal processes of the arytenoids. These ligaments are continuous with the lateral 

 parts of the crico-thyroid membrane, as the thickened and modified upper borders 

 of which they may be regarded (Fig. 1544)- Each band is triangular on section, 



having the free edge at that of the 

 Fig. 1544- 



Epiglottis, bent forward 

 Thyroid cartilage, left ala 



Superior cornii 

 of thyroid car- 

 tilage 



Cartilagje of 

 Santorini 



Arytenoid 

 cartilage 



Articular fac 

 for inferior thyroid 

 coriiu 



cord. There may be a minute 

 nodule of cartilage in the ligament 

 just in front of its posterior attach- 

 ment. 



Right thyroid 

 ala (cut) 

 Lateral part of 

 crico-thyroid mem- 

 brane attached to 

 vocal process 



Median part of crico- 

 thyroid membrane 

 Cricoid cartilage 



Trachea 



Ossification of the Larynx. — The 

 process, beginning a*s it does at about 

 twenty, is a normal change. Chievitz ' 

 found some ossification in every male 

 larynx of ov^er twenty and in every fe- 

 male one of over twenty-two. It ap- 

 pears at about the same time in the 

 cricoid and thyroid, — namely, at about 

 the beginning of the twentieth year, — 

 and in the arj'tenoid at about the mid- 

 dle of the twenties in man and nearer 

 the thirties in woman. 



The Cricoid. — The first nucleus 

 appears on each side at the back of 

 the facet for the arytenoid, and almost 

 at the same time another appears at 

 its front. These are shortly followed 

 by one at the joint for the thyroid. 

 These three unite, forming a lateral 

 ossification which spreads across the 

 back. One or more points appear in 

 front near the upper border of the arch, which is thus ossified and joins with the sides. After 

 these various unions the entire lower border of the cricoid is still cartilaginous. The youngest 

 man observed by Chievitz with complete ossification was forty-four and the youngest woman 

 seventy-six. 



The Thyroid. — The process begins near the posterior inferior angle and invades the in- 

 ferior horn. It appears next near the lower part of the anterior angle, and these two centres 

 on each side join by spreading along the inferior border. The superior horn then ossifies either 

 by a separate centre or by extension along the hind border. Finally a tongue-like process, 

 starting near the inferior tubercle, extends upward and forward across the ala to meet the ossi- 

 fication which has spread along the superior border, leaving before and behind it places which 

 are the last to ossify. This tongue-like process is peculiar to the male ; in the female ossifica- 

 tion advances chiefly from the posterior border. The youngest man with complete ossification 

 of the thyroid was fifty and the youngest woman seventy-six. 



The Arytenoids. — The process begins in the base. In man the starting-point is the mus- 

 cular process, but in woman it is less certain. The youngest man in whom the process was 

 complete was seventy-five and the youngest woman eighty-five. 

 The cartilago friticea, when present, also tends to ossify. 



Lateral view of larynx after removal of greater part of right 

 thyroid ala, showing attachment of crico-thyroid membrane to 

 arytenoid cartilage. The free border of the membrane constitutes 

 the thyro-arytenoid ligament and the framework of the vocal cord. 



THE FORM OF THE LARYNX AND ITS MUCOUS MEMBRANE. 



The shape of the larynx depends not only on the cartilages, but also on folds of 

 mucous membrane stretched over bands of connective tissue and over muscles. 



The cavity of the larynx is subdivided into three parts : the siipraglottic, the 

 glottic, and the infraglottic. 



The supraglottic region (vestibulum laryngis) begins with the entrance to the 

 laryn-x, an oval (or rather a heart-shaped) plane, which, owing to the height and 

 the position of the larynx, faces nearly backward. It is bounded by the free border 

 of the epiglottis in front and by the aryepiglottic fold which passes from this on 

 either side back over the top of the arytenoid cartilages. It is interrupted in the 

 median line behind by a notch. On either side of this the fold presents a small 

 swelling (tuberculum corniculatum), caused by the cartilage of Santorini, anterior to 

 which is a larger one (tuberculum cuneiforme) containing that of Wrisberg. Between 



* Archiv f. Anat. und Phys., Anat. Abth., 1882. 



