MUSCLES OF TUE LARYNX. 
449 
for although no veterinary anatomist that I have met with, Eng¬ 
lish or foreign, describes more than one, here are evidently three. 
A very slight dissection will bring them plainly into view. They 
are nearly parallel. You observe that they all spring from the 
anterior edge of the arytenoid cartilage. As we are travelling 
upward, I will take the lowest first. 
The Ligamento-arytenoideus Inferior .—It arises from the an¬ 
terior face of the tubercle of the spine of the arytenoid cartilage 
within the lateral crico-arytenoid muscle. It is not connected 
with the cricoid cartilage, and only with the thyroid by the 
loosest cellular membrane, but pursues its course anteriorly, 
closely bound to the lining membrane of the larynx by denser 
cellular substance, and, running parallel with, and nearly oppo¬ 
site to, but a little below the vocal ligaments, is inserted into the 
lower part of the oblique edge of the crico-thyroid ligament, or 
the ligament interposed between the alae of the thyroid cartilage. 
If we consider this muscle as contracting at its centre, the form 
of the larynx will be somewhat altered ; its posterior and anterior 
portions will be evidently approximated, and the elastic yielding 
nature of the ligament, and the moveableness of the arytenoid car¬ 
tilages, will permit this to some considerable extent; and thus the 
vocal ligaments will .be relaxed, and the rima glottidis widened 
and shortened. If the arytenoid cartilage is the fixed point, the 
interposed ligament will be drawn a little backw ards, and the lips of 
the glottis will be somewhat opened anteriorly at their apex or acute 
angle, and thus more air will be thrown on that membrane which 
I have described as placed over the point of the angle, and con¬ 
nected with the act of neighing. Accordingly, as the whole, or 
only a portion of this membrane is affected by the opening or 
closing of the angle, the neighing will be more rapid or distinct. 
If the membrane is the fixed point, we have an adjuvant to the 
muscle last described, drawing forward the base of the arytenoid 
cartilages, and thus bringing forward and separating the upper 
edses. 
The Ligamento-arytenoideus Medius .—This arises from the 
spine of the arytenoid cartilage, a little above the tubercles, and 
after pursuing the same course as the last along the external face 
of the lining membrane, but a little higher and above the vocal 
ligaments, and also being very loosely connected with the thyroid 
cartilage which covers this muscle, it is inserted into the central 
thickened portion of the same ligament, just above the inferior. 
1 he office of this muscle is clearly the same as the preceding. 
When, however, we consider their situation, tied down upon the 
lining membrane of the larynx, and the one a very little above, 
and the other as short a distance below the vocal ligaments, we 
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