H82 THE ORGANS OF VOICE AND RESPIRATION 



the larynx, bounded on either side by the arytenoepiglottidean folds, in which may be seen two 

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

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

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

 the bifurcation of the trachea. 



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

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

 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 dyspnea 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 arbove, more often the right. 



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

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

 tory affections, constituting the disease known as "edema of the glottis." This effusion does 

 not extend below the level of the true vocal cords, on account of the fact that the mucous mem- 

 brane 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 suffo- 

 cation, the operation of laryngotomy is sufficient. 



Chronic laryngitis is an inflammation of the mucous membrane 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 surgically in two different situations through the cricothyroid 

 membrane {laryngotomy), or in some part of the trachea (tracheotomy); and to these some sur- 

 geons ha*ve added a third method opening the cricothyroid membrane and dividing the car- 

 tilage with the upper ring of the trachea (laryngotracheotomy). 



iMryngotomy 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 cricothyroid membrane is very super- 

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

 On each side of the middle line it is also covered by the Sternohyoid and Sternothyroid 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 connec- 

 tion with this operation is the cricothyroid artery, which crosses the cricothyroid 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 cricothyroid 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 cricothyroid artery, and a 

 tracheotomy tube is introduced. It has been recommended, as a more rapid way of performing 

 the operation, to make a transverse instead of a longitudinal cut, through both the superficial and 

 deep structures, and thus to open at once the air passages. It will be seen, however, that in 

 opening in this way the anterior jugular veins would be in danger of being wounded. 



Tracheotomy may be performed either above or below the isthmus of the thyroid body, or 

 this structure may be divided and the trachea opened behind it. 



The isthmus of the thyroid gland usually crosses the second and third rings of the trachea; 

 along its upper border is frequently to be found a large transverse communicating branch between 

 the superior thyroid veins; and the isthmus itself is covered by a venous plexus formed between 

 the thyroid veins of the opposite sides. Theoretically, therefore, it is advisable to avoid dividing 

 this structure in opening the trachea. 



Above the isthmus the trachea is comparatively superficial, being covered by the skin, super- 

 ficial fascia, deep fascia, Sternohyoid and Sternothyroid muscles, and a second layer of the deep 



