ORGANS OF RESPIRATION AND VOICE. 177 



joins the body, there is a small process called the appendix, which ascends 

 obliquely backwards, and gives attachment to the stylo-hyoid muscle and 

 ligament. When, as sometimes happens, this ligament is ossified, the os 

 hyoides becomes attached directly to the cranium. 



2. Cartilages of the Larynx. Four true or perfect, and four false or 

 imperfect cartilages enter into the composition of the larynx. The former 

 are the thyroid, cricoid, and two arytenoid ; the latter are the two corpora 

 euneiforma, and the appendices or cornicula of the arytenoid cartilages; 

 there is also one fibro-cartilage, the epiglottis. 



The thyroid cartilage is placed at the anterior and lateral parts of the 

 larynx. It is composed of two broad lateral plates, connected in an anterior 

 median prominence, known as the pomum Adami or Adam''s apple, and 

 larger in the male than in the female. The posterior surface of the pomum 

 gives attachment to the ligament of the epiglottis and to the chordae 

 vocales. 



The cricoid, or annular cartilage, forms the lower part of the larynx. The 

 inferior edge is nearly circular and horizontal, and gives attachment to the 

 first ring of the trachea; the superior margin is oblique, and separated from 

 the thyroid cartilage by the crico-thj'-roid ligament. 



The arytenoid cartilages are situated vertically on the articulating sur- 

 faces on the upper and posterior border of the cricoid. The base of each 

 presents two processes, one for the attachment of the crico-arytenoid muscle, 

 the other for the insertion of the inferior chorda vocalis. The apex of each 

 arytenoid inclines a little backwards, and is surmounted by the appendix, 

 or corniculum. The internal or opposed sides of the arytenoid cartilages 

 are smooth, and covered by mucous membrane, so as to admit of their 

 approximation. 



The epiglottis stands behind the base of the tongue, nearly erect in front 

 of the opening of the glottis, over which it can be bent almost horizontally, 

 so as to cover this opening during deglutition. In form it is somewhat 

 triangular or oval, so as to resemble a cordate leaf, with the edges slightly 

 curled. 



The larynx is articulated or connected to the os hyoides by three hyo- 

 thyroid ligaments, one middle and two lateral. The thyro-arytenoid liga- 

 ments, or chordae, vocales, are four in number, two on each side, a superior 

 and an inferior. The ligaments of the epiglottis are the thyro-ejnglottidean, 

 the hyo-epiglottidean, and the frcBnum epiglottidis. This latter, however, is 

 only a fold of mucous membrane, connecting the epiglottis with the tongue. 



3. Muscles of the Larynx. The muscles of the larynx are symme- 

 trical ; they are found on the front, sides, and back part. Those on the fore 

 part are the thyro-hyoid and crico-thyroid ; those on each side are the thyro 

 and lateral crico-arytenoid ; the muscles of the back part are the arytenoid 

 and the posterior crico-arytenoid. 



The openings of the larynx are two, the superior or the glottis, and the 

 inferior or the tracheal. The superior opening, or the glottis, is at the 

 lower and anterior part of the pharynx, behind the epiglottis and rather 

 beneath the tongue. It is of a triangular form, the base anteriorly formed 



883 



