THE VOICE. 



823 



$ 758 Narrowing of the glottis. The change of form of the glottis is 

 best understood when it is borne in mind that each arytenoid cartilage is, 

 when seen in horizontal section (Fig. 208), somewhat of the form of a tri- 

 angle with an internal or median, an external, and a posterior side, the pro- 

 cessus vocalis being placed in the anterior angle at the j unction of the 

 median and external sides. When the cartilages are so placed that the pro- 

 cessus vocales are approximated to each other, and the internal surfaces 



FIG. 208. 



A' 



The Larynx as Seen by Means of the Laryngoscope in Different Conditions of the Glottis. 

 (From Quain's Anatomy, after Czermak.) A, while singing a high note ; B, in quiet breathing; 

 C, during a deep inspiration. The corresponding diagrammatic figures A', B', C', illustrate the 

 changes in position of the arytenoid cartilages and the form of the rima vocalis and rima re- 

 spiratoria in the above three conditions. I, the base of the tongue ; e, the upper free part of the 

 epiglottis ; e', the tubercle or cushion of the epiglottis ; ph, part of the anterior wall of the 

 pharynx behind the larynx ; w, swelling in the aryteno-epiglottidean fold caused by the carti- 

 lage of Wrisberg; s, swelling caused by the cartilage of Santorini ; a, the summit of the ary- 

 tenoid cartilage; cv, the true vocal cords; cvs, the false vocal cords; tr, the trachea with its 

 rings ; 6, the two bronchi at their commencement. 



the cartilages nearly parallel, the glottis is narrowed. When on the con- 

 trary the cartilages are wheeled round on the pivots of their articulations, so 

 that the processus vocales diverge, and the internal surfaces of the cartilages 

 form an angle with each other, the glottis is widened. 



759. There are several muscles forming together a group which has 

 been called by Henle the sphincter of the larynx. These are : 1, the thyro- 

 ary-epiglotticus, proceeding from the inner surface of the thyroid cartilage 

 and from the arytenoid epiglottidean ligament, and sweeping round the outer 

 ridge of the arytenoid cartilage of its own side to be inserted into the pro- 

 cessus muscularis of the arytenoid cartilage of the other side ; 2, the thyro- 

 arytenoideus externus, passing from the reentrant angle of the thyroid carti- 

 lage to be inserted into the outer edge of the arytenoid cartilage of the same 



