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. _W-hen, 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, 
cuneiforma, 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 chordz 
voeales. 
The ericoid, 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-thyroid 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 appendia, 
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 epzglottis 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 a8to cover this opening during deglutition. In form it is somewhat 
triangular or oval, so as to resemble a pealae. 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 chordce vocales, are four in number, two on each side, a superior 
and an inferior. The ligaments of the epiglottis are the thyro-epiglottidean, 
the hyo-epiglottidean, and the frenum epiglottidis. This latter, however, is 
only a fold of mucous membrane, connecting the epiglottis with the tongue. 
3. MUSCLES OF THE LarRyNx. 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 
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