MUSCLES OF THE LARYNX. 
453 
This is a curious and interesting fact; it must, however, be ad¬ 
mitted with some limitation. The broad assertion, first made I 
believe by M. Majendie, of this distribution of nervous influence 
to the dilators and constrictois, from different branches of the 
par vagum, is thus far true, that none of the laryngeal branches 
have been traced to the dilators; but I am sure that I have 
traced many fibres of the recurrent nerve to the constrictors. 
Still I say, the fact is singular enough. 
The Experiments of Le Gallois. — Experiments, and most 
satisfactory, are related by Sir Charles Bell. Le Gallois found 
that a division of the laryngeal branch stopped the consent of 
motion between the muscles of the glottis and the muscles of 
the chest. The innumerably varied expansion of the glottis, and 
of the anterior cartilages, ceased at once; all the cartilages of 
the larynx but one had lost the power to move. The voice, how¬ 
ever, remained; for the arytenoid muscle, derived from another 
source, continued to act, and the glottis was contracted, and the 
vocal ligaments were rendered tense, and they vibrated sufficiently 
rapidly and powerfully ; and the animal could tell the pain he 
suffered under the cruel experiments. 
In another case the laryngeal branch of the par vagum was 
left untouched, but the recurrent branch was divided. The con¬ 
sent of motion between the respiratory muscles and the natural 
process of respiration were very little interrupted, but the voice 
was destroyed, for neither the arytenoid cartilages nor the glottis 
could contract. 
The common sensibility of the larynx is derived partly from 
anastomoses with descending branches of the fifth pair of nerves, 
but more from the first and second cervical nerves. 
The Bloodvessels. —The origin of the laryngeal artery is not 
always uniform. In a few instances it is derived from the main 
trunk of the carotid ; but in the majority of cases it is a branch 
of the thyroideal artery. It pierces the ligament between the 
thyroid and cricoid cartilage, about the middle of the side of the 
larynx, and is diffused over the lining membrane of the larynx, 
and the muscles of this organ. The ascending pharyngeal, how¬ 
ever, affords some branches to the larynx, and other small 
branches may be traced. The veins follow nearly the same 
course as the arteries, and empty themselves into the jugular. 
The Sensibility of the Membrane , how regulated , and the con¬ 
sequence of this. — lhe lining membrane of the larynx is a con¬ 
tinuation of that of the pharynx above and of the trachea 
below. It is covered with innumerable follicular glands, from 
whose mouths there oozes a mucous fluid that moistens and 
lubricates its surface. 
It is possessed of very great sensibility; 
