THE LARYNX 



1171 



Wi\\ EPIGLOTTIC 



membrane. The posterior cricoarytenoid ligament extends from the cricoid to 

 the inner and back part of the base of the arytenoid cartilage. 



The thyroepiglottic ligament (ligamentum thyreoepiglotticum) (Fig. 884) is a 

 long, slender elastic cord which connects the apex of the epiglottis with the internal 

 surface of the receding angle of the thyroid cartilage, immediately beneath the 

 median notch, above the attachments of the false and true vocal cords. 



Movements. The articulation between the inferior cornu of the thyroid and the cricoid 



cartilage on either side is a diarthroidal one, and permits of rotary and gliding movements. 

 The rotary movement is one in which the inferior cornua of the thyroid cartilage rotate upon 

 the cricoid cartilage around an axis passing transversely through both joints. The gliding 

 movement consists in a limited shifting of the cricoid on the thyroid in different directions. 



The articulation between the arytenoid cartilages and the cricoid is also a diarthrodial one, 

 and permits of two varieties of movement one a rotation of the arytenoid on a vertical axis, 

 whereby the vocal process is moved outward or inward and the opening of the rima glottidis 

 increased or diminished; the other is a gliding movement and allows the arytenoid cartilages 

 to approach or recede from each other; from the direction and slope of the articular surfaces 



- outward gliding is accompanied by a forward and downward movement. The two movements 

 of gliding and rotation are associated, the gliding inward being connected with inward rota- 

 tion, and the gliding outward with oiltward rotation. The posterior cricoarytenoid ligaments 

 limit the forward movement of the arytenoid cartilages on the cricoid. 



Interior of the Larynx (Figs. 883, 884, and 887). The cavity of the larynx 

 (cavum laryngis) extends from the superior aperture of the larynx to' the lower 

 border of the cricoid cartilage. It is divided into two parts by the projection 

 inward of the true vocal 

 cords, between which is 



a narrow triangular fis- ( X \ 



sure or chink, the rima \ 



glottidis. The portion 

 of the cavity of the 

 larynx above the true 

 vocal cords, sometimes 

 called the vestibule 

 (vestibulum laryngis), is 

 wide and triangular in 

 shape, its base or an- 

 terior wall presenting, 

 however, about its centre 

 the backward projection 

 of the cushion of the 

 epiglottis. It contains 

 the false vocal cords 

 (plicae ventriculares), 

 and between these and 

 the true vocal cords are 

 the ventricles of the 

 larynx. The portion 

 below the true vocal 

 cords is at first of an 

 elliptical form, but lower 



down it widens out, assumes a circular form, and is continuous with the tube of 

 the trachea. 



The Superior Aperture of the Larynx (aditus laryngis) (Figs. 883 and 887). is 

 a triangular or cordiform opening, wide in front, narrow behind, and sloping 

 obliquely downward and backward. It is bounded, in front, by the epiglottis; 

 behind, by the apices of the arytenoid cartilages and the cornicula laryngis; and' 



THYRO-EPIGLOT 

 TIC LIGAMENT 



ARYTENO-EPI- 

 GLOTTIOIAN FOLD 



CRICOID 

 RTILAGE 



FIG. 884. Sagittal section of larynx, right half. (Testut.) 



