968 THE ORGANS OF VOICE AND RESPIRATION. 



Surface Form. In the middle line of the neck some of the cartilages of the larynx can be 

 readily distinguished. In the receding angle below the chin the hyoid bone can easily be made 

 out (see page 126), and a finger's breadth below it is the pomum Adami, the prominence between 

 the upper borders of the two alse of the thyroid cartilage. About an inch below this, in the 

 middle line, is a depression corresponding to the crico-thyroid space, in which the operation of 

 laryngotomy is performed. This depression is boimded below by a prominent arch, the anterior 

 ring of the cricoid cartilage, below which the trachea can be felt, though it is only in the emaci- 

 ated adult that the separate rings can be distinguished. The lower part of the trachea is not 

 easily made out, for as it descends in the neck it takes a deeper position, and is farther removed 

 from the surface. The level of the vocal cords corresponds to the middle of the anterior margin 

 of the thyroid cartilage. 



With the laryngoscope, the following structures can be seen : The base of the tongue and 

 the upper surface of the epiglottis, with the glosso-epiglottic ligaments ; the superior aperture of 

 the larynx, bounded on either side by the aryteno-epiglottidean folds, in which may be seen two 

 rounded eminences corresponding to the cornicula and cuneiform cartilages. Beneath these, the 

 true and false vocal cords, with the ventricle between them. Still deeper, the cricoid cartilage 

 and some of the anterior parts of the rings of the trachea, and sometimes, in deep inspiration, 

 the bifurcation of the trachea. 



Surgical Anatomy. Foreign bodies often find their way into the air-passages. These may 

 be either large soft substances, as a piece of meat, which may become lodged in the upper aper- 

 ture of the larynx or in the rima glottidis, and cause speedy suffocation unless rapidly got rid of, 

 or unless an opening is made into the air-passages below, so as to enable the patient to breathe. 

 Smaller bodies, frequently of a hard nature, such as cherry or plum stones, small pieces of bone, 

 buttons, etc., may find their way through the rima glottidis into the trachea or bronchus, or may 

 become lodged in the ventricle of the larynx. The dangers then depend not so much upon the 

 mechanical obstruction as upon the spasm of the glottis which they excite from reflex irritation. 

 When lodged in the ventricle of the larynx, they may produce very few symptoms beyond 

 sudden loss of voice or alteration in the voice sounds, immediately following the inhalation of 

 the foreign body. When, however, they are situated in the trachea, they are constantly striking 

 against the vocal cords during expiratory efforts, and produce attacks of dyspnoea from spasm 

 of the glottis. When lodged in the bronchus, they usually become fixed there, and, occluding 

 the lumen of the tube, cause a loss of the respiratory murmur on the affected side, which is, as 

 stated above, more often the right. 



Beneath the mucous membrane of the upper part of the air-passages there is a consider- 

 able amount of submucous tissue which is liable to become much swollen from effusion in 

 inflammatory affections, constituting the disease known as "oedema of the glottis." This 

 effusion does not extend below the level of the vocal cords, on account of the fact that the 

 mucous membrane is closely adherent to these structures, without the intervention of any 

 submucous tissue. So that, in cases of this disease in which it is necessary to open the air- 

 passages to prevent suffocation, the operation of laryngotomy is sufficient. 



Chronic laryngitis is an inflammation of the mucous glands of the larynx, which occurs in 

 those who speak much in public, and is known as " clergyman's sore throat." It is due to the 

 dryness induced by the large amount of cold air drawn into the air-passages during prolonged 

 speaking, which incites increased activity in the mucous glands to keep the parts moist, and 

 this eventually terminates in inflammation of these structures. 



Ulceration of the larynx may occur from syphilis, either as a superficial ulceration, or from 

 the softening of a gumma ; from tuberculous disease (laryngeal phthisis), or from malignant 

 disease (epithelioma). 



The air-passages may be opened in two different situations: through the crico-thyroid 

 membrane (laryngotomy), or in some part of the trachea (tracheotomy)', and to these some 

 surgeons have added a third method, by opening the crico-thyroid membrane and dividing the 

 cricoid cartilage with the upper ring of the trachea (laryn go-tracheotomy}. 



Laryngotomy is anatomically the more simple operation : it can readily be performed, and 

 should be employed in those cases where the air-passages require opening in an emergency for 

 the relief of some sudden obstruction to respiration. The crico-thyroid membrane is very 

 superficial, being covered only in the middle line by the skin, superficial fascia, and the deep 

 fascia. On each side of the middle line it is also covered by the Sterno-hyoid and Sterno- 

 thyroid muscles, which diverge from each other at their upper parts, leaving a slight interval 

 between them. On these muscles rest the anterior jugular veins. The only vessel of any 

 importance in connection with this operation is the crico-thyroid artery, which crosses the crico- 

 thyroid membrane, and which may be wounded, but rarely gives rise to any trouble. The 

 operation is performed thus : the head being thrown back and steadied by an assistant, the 

 finger is passed over the front of the neck, and the crico-thyroid depression felt for. A vertical 

 incision is then made through the skin, in the middle line over this spot, and carried down 

 through the fascia until the crico-thyroid membrane is exposed. A cross cut is then made 

 through the membrane, close to the upper border of the cricoid cartilage, so as to avoid, if 

 possible, the crico-thyroid artery, and a tracheotomy tube introduced. It has been recommended, 

 as a more rapid way of performing the operation, to make a transverse instead of a longitudinal 

 cut, through the superficial structures, and thus to open at once the air-passages. It will be 

 seen, however, that in operating in this way the anterior jugular veins would be in danger of 

 being wounded. 



