426 MR. youatt’s veterinary lectures. 
to it and to the thyroid cartilage above, and occasionally bring¬ 
ing these cartilages closer together. Posteriorly it spreads out 
into an irregular hexagonal surface, giving to the whole of the 
cartilage the form of a ring with a broad expanse for the setting 
of the jewel. This expanse has a spine in the centre, with a 
roughened depressed surface on each side, for the insertion of 
muscles connected with the arytenoid cartilages above ; and there 
are likewise at the four corners of this expanse little tubercles or 
prominences forming articulations with the other cartilages— 
perfect joints provided with capsular ligaments and synovial 
membranes, and thus admitting great freedom of action among 
the cartilages of the larynx. The two superior ones articulate 
with the arytenoid cartilages, the two inferior ones with the 
thyroid. 
The Arytenoid Cartilages .—These are placed above, and rest 
upon the cricoid cartilage, articulating posteriorly with the tuber¬ 
cular prolongation which I have just pointed out to you ;—they 
are connected laterally and inferiorly with the thyroid cartilage by 
cellular membrane, and anteriorly with the epiglottis at its base. 
Prolongations of them extend to and rest upon the chordae 
vocales beneath, and doubtless influence their action. They are 
connected together posteriorly by cellular membrane and the 
fibres of the arytenoid muscle. Taken separately, they are of 
a triangular form, presenting, as you perceive, the principal 
angle laterally and anteriorly, and the base, presented posteriorly, 
being most irregularly formed. Posteriorly, and somewhat 
laterally, is a thickness of cartilage not found in any of the 
others, consisting of a strong spine, with a hollow on each side 
for the insertion of muscles. This strength of cartilage is placed 
here, because at this spot the larynx is most exposed to lateral 
pressure. The posterior point of the arytenoid cartilage con¬ 
stitutes one extremity of the irregular base of this triangle, and 
the tubercle of the cartilage the other extremity. The supe¬ 
rior and unattached portions are curved and the edges bent 
round, and leave between them a triangular fissure with its base 
anteriorly, and which is the opening into the larynx. 
The two cartilages here separate, but, uniting posteriorly, bear 
no indistinct resemblance to the lip or mouth of a ewer, and 
thence their name. 
The Epiglottis .—This is a heart-shaped cartilage, springing 
from the anterior part of the larynx. Its base is composed of 
two slips of cartilage which run along the inside of the thyroid 
cartilage, attached to it by cellular membrane and ligamentous 
substance, forming one of the borders of the sacculus laryngis, 
and extending to the arytenoid cartilages. At the centre of its 
