The most difficult part of the pathology of the larynx to contend with is that which has reference to muscular organization, and unfor tunately it is that which has been least ex amined, or on which examination has thrown the faintest and most unsatisfactory light. Furnished with an exquisitely delicate and beautiful arrangement of muscle, the normal actions of which are exemplified in the pro duction of the different sounds of the voice, and in giving force to the exit of the air in coughing, sneezing, &c. it would appear only reasonable to suppose that the functional de rangements of the larynx should be accom panied by some appreciable corresponding le sion of its muscular apparatus ; yet such does not seem to be the case, at least not invariably, and we sometimes find the voice impaired or perhaps lost, the muscles of the organ ex hibiting their ordinary appearance, and again remarkable and seemingly important lesions without much injury to voice or respiration. Under these circumstances we must speak of the morbid appearances that have been ob served in the first instance, and consider the irregularities of function afterwards.
The muscles of the larynx are sometimes found in a state of extraordinary develope ment amounting almost to hypertrophy. I know not how far this may be considered to be an abnormal condition, or whether it may not be the natural result of great and constant em ployment of the organ : reasoning from ana logy this latter seems more probable, but dis section has hitherto thrown no light upon the subject.
They are likewise subject to atrophy or wasting, the fibres appearing thin, pale, and attenuated. Andral mentions cases of loss of voice in which he sometimes found the fibres of the thyro-arytenoid muscle wonderfully atro phied, and sometimes separated from each other by some morbid secretion, either of pus or tubercular matter. I have been informed by Sir P. Crampton that he has seen in the Mu seum of the Veterinary College in London, several preparations illustrative of the disease termed" roaring" in the horse, which seems to be produced by an atrophy of the arytenoid muscles. A relaxation is thus effected which allows to the arytenoid cartilages an unnatural degree of mobility. Whilst the animal is at rest or moving slowly, the current of air passes gently, and there is no " roaring ;" but when he is put to greater speed and respiration becomes more hurried or more forced, the little valves are acted on, the rima is proportionably closed, the breathing becomes stridulous, and that pe culiar noise so well known to persons conver sant with horses is produced.
Lesion of function in the muscles of the la rynx exhibits itself in the opposite conditions of atony and spasm. Examples of the former are to be found in some cases of partial pa ralysis where the patients become totally in capable of uttering any sound, however in distinct and inarticulate ; in the hoarseness and sometimes loss of voice that suddenly attacks young persons, particularly females, from ex posure to cold and damp ; and perhaps fre quently inthe sympathetic aphonia that precedes or attends on phthisis. On the pathology of these affections morbid anatomy has thrown but little light, nor is it surprising that the subject has attracted a minor degree of attention, when it is recollected that the more severe laryngeal symptom, that of difficult respiration, is seldom or never present. I have had two cases of aphonia attended with pain and soreness in the larynx, which, under an idea that the disease was either gout or rheumatism, I treated with colchicum with apparently favourable results. I know not whether the supposition that the la rynx may be the seat of either of these painful affections is correct or not, but I see no reason why it should enjoy so fortunate an exemption. However, although atony of the muscles of the larynx may not be attended with much peril, a spasmodic action of them is always eminently perilous, sometimes destroying life with a ra pidity that almost precludes the possibility of assistance. There can, therefore,'be few sub jects more interesting to the practitioner, and although, as might be expected, the causes that produce these terrific affections have not been explained, yet it may be desirable to examine into the symptoms and some of the circum stances that occasionally precede or accompany them.
Spasm of the glottis is either idiopathic or symptomatic.
The idiopathic occurs, as far as I know, only in children, as in the "spasmodic croup," or laryngismus stridulus, unless we also choose to include within this class the hysteric dyspneea that occurs in young females.
The symptomatic occurs as indicative of, or in connexion with, 1. The application of some deleterious sub stance to the larynx, as carbonic acid, boiling water, or steam.
2. The application of some irritating mate rial, as a particle of salt.
3. The presence of a foreign body within the trachea or bronchial tubes.
4. The presence of a foreign body in the (esophagus.
5. The existence (occasionally) of an aneur ism of the aorta.