388 THE POPULAR SCIENCE MONTHLY. 



the V turned forward. In women it is less prominent than in men, 

 and it is known as Adam's apple. The lateral cartilages, which spring 

 from the ring-cartilage at the back of the larynx, assume the form of 

 little triangular pyramids with uneven surface. They are slightly 

 curved toward the upper extremity, and support a little horny plate, 

 which in the eyes of the ancient anatomists resembled the snout of a 

 pitcher. 1 The lateral cartilages, being very mobile, play an important 

 part in the emission of the voice. 



The larynx is to some extent movable. Being attached to the 

 hyoid or tongue bone by means of a membrane strengthened by liga- 

 ments, it is lifted up by the action of muscles extending from the 

 tongue-bone to the external surface of the thyroid cartilage ; it is 

 pulled down by the action of muscles which extend from this same 

 cartilage to the sternum. Further, the vocal apparatus is affected by 

 the movements of the pharynx and of the tongue, as also by the 

 respiratory movements. The solid parts of the larynx, being more or 

 less movable, change position under the action of muscles which pass 

 from one to another of them. Bundles of muscular fibre which spring 

 from the annular cartilage (the cricoid) cause the thyroid cartilage 

 to move up and down, and this movement produces tension of the 

 vocal cords. Muscles springing from the cricoid and from the thy- 

 roid produce a rotation of the lateral cartilages, and modify the con- 

 ditions of the cords. Finally, there are bundles of muscular fibre 

 extending from one lateral cartilage to the other; when these con- 

 tract, the walls of the larynx are brought nearer to each other, and 

 the opening through which the air passes is made narrower. 



Internally, the larynx is lined with mucous membrane, which is 

 continuous with the mucous membrane of the mouth. Two pairs of 

 ligaments, extending from the thyroid to the arytenoid, divide the 

 cavity into compartments. The lower portion is limited by an arch 

 formed of thick folds of mucous membrane. The middle portion is 

 distinguished by the presence of folds supported by ligaments. These 

 are the vocal cords, which play the principal part in the act of pho- 

 nation. The superior cords, which resemble thin bands, occupy both 

 sides. The inferior cords, or true vocal cords, which are very thick, 

 are situated beneath the upper, and extend considerably beyond 

 them toward the median line. 2 They bound the orifice called the 

 glottis. This orifice, which in the state of repose is triangular in 

 shape, varies constantly in form and in dimensions under the influence 

 of respiration and the emission of the voice. This use of the term glot- 

 tis, which signifies toxyue, to designate an orifice, is very curious, and is 



1 The ring-cartilage is the cricoid cartilage of the anatomists ; the T-shaped cartilage 

 is the thyroid ; the lateral cartilages are the right and left arytenoids ; and the little plate 

 they bear, the cartilages of Santorini. 



' On each side, between the superior and inferior vocal cords, occuis a large cavity. 

 These cavities are known as Morgagni's ventricles. 



