JOINTS AND LIGAMENTS OF THE LARYNX. 913 
The lateral part on each side presents very different connexions. It is not attached 
to the lower border of the thyroid cartilage, but slopes upwards and inwards within 
the thyroid ala, and thus diminishes m: .terially the transverse width of the lower 
subdivision of the laryngeal cavity. Its 
attachments are very definite.  elow, it 
is fixed to the upper border of the cricoid 
cartilage, immediately subjacent to the 
lining mucous membrane of the larynx ; 
above, 1t is directly continuous with the 
inferior thyro-arytenoid ligament or sup- 
porting band of the true vocal cord. This 
ligament, indeed, may be looked upon 
as constituting the upper thickened free 
border of the lateral part of the crico- 
thyroid membrane. Jn front, the lateral 
part of the crico-thyroid membrane is 
attached to the lower half of the inner 
surface of the ala of the thyroid cartilage, 
close to the angle, and behind, to the 
lower border of the processus vocals of 
the arytenoid cartilage. In contact with 
the outer surface of the lateral part of Fic. 615.—DissEcTIoN TO SHOW THE LATERAL PaRT 
the crico-thyroid membrane, and separat- OF THE CRICO-THYROID LDR The oo 
ing it from the thyroid ala, are the lateral ala of the thyroid cartilage has been removed. 
erico-thyroid and the thyro-arytenoid muscles; the inner surface is clothed by 
the lining mucous membrane of the larynx. 
Inferior Thyro-arytenoid eee (ligamentum vocale).—This is formed 
in connexion with the upper border of the lateral part of the crico-thyroid 
membrane, and it constitutes the supporting ligament of the true vocal cord. It 
is attached in front, close to its fellow of the opposite side, to the middle of the 
angular depression between the two ale of the thyroid cartilage. From this it 
stretches backwards, and becomes incorporated with the tip and upper border of the 
processus vocalis which projects forwards from the base of the arytenoid cartilage. 
The inferior thyro-arytenoid ligament is composed of yellow elastic fibres, and 
embedded in its anterior extremity there is frequently a minute nodule of elastic 
cartilage. Its inner border is sharp and free, and is clothed by mucous membrane, 
which in this position is very thin and tightly bound down to the ligament. 
The superior thyro- arytenoid ligament (ligamentum ventriculare) supports 
the false vocal cord. It is weak and indefinite, but somewhat longer than the 
preceding ligament. In front it is attached to the angular depression between the 
two alz of the thyroid cartilage, above the true vocé al ligaments and close to the 
attachment of the thy ro- epiglottidean ligament, and it extends backwards to be fixed 
to a tubercle on the antero-external surface of the arytenoid cartilage, a short dis- 
tance above the processus vocalis. It is composed of connective tissue and elastic 
fibres which are continuous with the fibrous tissue in the ecb epiglottidean fold. 
Epiglottidean Ligaments.—The epiglottis is bound by hgaments to the base 
of the tongue, to the hyoid bone, and to the thyroid cartilage. The glosso-epi- 
glottidean eaments are three in number, viz. a middle onde two lateral. The 
middle glosso-epiglottidean ligament (plica glosso-epiglottica mediana) is a prominent 
mesial fold of mucous membrane which proceeds from the middle of the anterior 
free surface of the epiglottis to the base of the tongue. The lateral glosso-epiglotti- 
dean ligaments (plicze glosso-epiglotticee laterales) are similar mucous folds which 
proceed from the margins of the epiglottis to the side of the base of the tongue and 
to the pharyngeal wall. From the latter attachment they are sometimes called the 
pharyngo-epiglottic folds. Between the two layers of mucous membrane which 
form each of these three folds there is a certain amount of elastic tissue. By the 
glosso-epiglottidean folds the depression between the root of the tongue and the 
epiglottis is marked off into two fossee termed the vallecule. 
The hyo-epiglottidean ligament (ligamentum hyoepiglotticum) is a short, broad 
58 
Arytenoid cartilage 
Muscular process 
_Yoeal process 
Rina glottidis 
Ligament of true 
—~ vocal cord 
Lateral part of crico- 
“4 thyroid membrane 
W Facet on ericoid for inferior 
cornu of thyroid cartilage 
ma Cricoid cartilage 
