Partial paralysis of the constrictors may be due to deficient power of one or both of the laryngeal nerves, superior or inferior. The parts involved are the arytenoids, transverse and oblique, and the muscular fibres in the folds going from the arytenoid and from the thyroid cartilages to the epiglottis. The ETIOLOGY of this form of paralysis associates itself with that of anæsthesia of the parts--namely, the arrest of motor impression in the centre, obstruction along the course of the nerve, disease in the nerve itself, in its trunk or termination, or, lastly, myopathic changes rendering the muscle incapable of responding to the nervous influences. Disease in the centres may possibly affect only these muscles; the disorders of motion may be well defined and local in extent, but usually, in case of central disease, there is a complication of external manifestations and we have a wider range of disturbances. The most common cause of this loss of power is diphtheria. SYMPTOMS.--The symptoms of paralysis of the constrictors of the larynx are for the most part mechanical. The failure to close the vestibule of the organ in the act of swallowing allows food or drink to pass into the larynx, {81} and, as there is usually anæsthesia of the parts also, the invasion of the larynx is not perceived; no reflex irritation is produced, no cough for the extrusion of the offending matter, which may descend into the trachea, and, reaching the bronchi, may become the agent in the development of a bronchitis or a broncho-pneumonia. The secretions of the mouth overflow the borders of the laryngeal opening and fall into the tube below. Fluids are swallowed with greater difficulty than solids. The voice is not altered except in cases where the crico-thyroids, one or both, are involved, as in complete paralysis of the superior laryngeal nerve. The effort to close the glottis, as in the preliminary act of coughing, is accomplished with difficulty. The sound of the cough is somewhat altered. This is for want of the reinforcement to the adductors furnished by the closure of the vestibule of the larynx. Upon laryngoscopic examination the epiglottis is seen to stand erect against the dorsum of the tongue. The ary-epiglottic folds are lax or wide apart. With this is loss or diminished sensibility of the surfaces. There is little or no change in the color of the membranes. The secretions are normal in quality, and only slightly in excess in quantity. The course of the disease is in cases of diphtheritic origin like that of anæsthesia from the same cause. The termination, except in rare instances, is recovery. In cases of central origin the local symptoms in the larynx are almost necessarily associated with disorders of other parts. The progress and termination will depend upon the nature and extent of the central lesion.