PRACTICAL CONSIDERATIONS : THE LARYNX. 1831 



base) during quiet respiration, and diamond- shaped (with the posterior angle cut 

 off) in forced breathing. As various forms of ulceration (tuberculous, syphilitic, 

 diphtheritic) may affect the mucous membrane covering the true vocal cords, or the 

 cords themselves, or the structures in their immediate vicinity (especially the aryteno- 

 epiglottidean and interarytenoid folds and the ventricular bands), and as cicatrization 

 with subsequent contraction of scar tissue may follow, diminution of the calibre of 

 the rima glottidis (stricture) is not uncommon. 



Polyps, warty growths, and other benign tumors are found in the vicinity of the 

 vocal cords, and if they cannot be removed by intralaryngeal operation, may neces- 

 sitate thyrotomy. Subglottic tumors are relatively infrequent. They often spring 

 from the inferior surface of the vocal cords, intraglottic growths from the free 

 border of the anterior part of the vocal cords, and supraglottic growths from the 

 epiglottis and the aryteno-epiglottic folds (Delavan). 



Spasm of the glottis (laryngismus stridulus) may occur, especially in infancy, 

 from reflex irritation, and may cause great dyspnoea or may even result fatally. The 

 irritation is conveyed chiefly. to the inferior laryngeal nerves through the pneumo- 

 gastrics, if the cause is undigested food ; through the trifacial, if the irritation is asso- 

 ciated with dentition ; or through the spinal accessory, if vertebral disease is present. 



The different forms of laryngeal paralysis should be studied in connection with 

 the physiology of phonation. Some of the chief anatomical considerations may be 

 indicated by the following classification, which is, however, necessarily incomplete, 

 as failing to include the central causes of paralysis — as in bulbar palsy — and those 

 due to toxaemia, as the post-diphtheritic. 



1. Those due to direct or indirect involvement of the superior larymgeal nerves, 

 (a) Sensory and thyro-epiglottic — or aryepiglottic — paralysis, characterized by a 



tendency of food or liquids to enter the larynx, by dysphagia, by immobility of the 

 epiglottis, and by diminished sensation in both the pharyngeal and laryngeal mucous 

 membranes, would suggest especial implication of the internal branch. 



{b') Crico-thyroid and thyro-arytenoid paralysis, causing loss of tension in the 

 vocal cords, inability to regulate and control the voice, and with evidence of the 

 want of action of the crico-thyroids detected by the finger placed on either side of 

 the crico-thyroid interval externally during phonation (Agnew), may, in some cases, 

 be referred anatomically to the external branch. 



2. Those due to involveinent of the inferior laryngeal iierves. 



(a) Lateral crico-arytenoid paralysis, causing separation of the vocal cords, 

 with more or less complete aphonia, may be due to implication of the external 

 branch. In many cases there will be evidence of the existence of innominate or 

 aortic aneurism, thyroid or bronchial glandular enlargement, carcinoma of the oesoph- 

 agus, or some other condition competent to produce pressure on the nerve. The 

 paralysis may be unilateral and attended only by hoarseness and partial loss of voice. 



{b') In posterior crico-arytenoid paralysis (abductor paralysis) the loss of power 

 in the abductors permits the lateral crico-arytenoid muscles to narrow the glottis 

 into a mere fissure, so that inspiration becomes stridulous and dyspnoea is marked ; 

 the voice is not materially interfered with. The condition may be due to intra- 

 or extralaryngeal growths, or to inflammatory conditions, possibly causing pressure 

 on the inner branch. It may be unilateral and due to aneurism. 



It should be understood that the relation of these paralyses to the external and 

 internal branches of the superior and inferior laryngeal nerves cannot be demonstrated 

 clinically with definiteness. Pressure on the main trunk of either nerve, tabes, 

 hysteria, toxaemia, and other central or general causes may produce any of these 

 forms of paralysis. 



In intubation of the larynx (employed in some forms of acute stenosis, as in 

 diphtheria or oedematous laryngitis) an irregular cylindrical tube with a fusiform 

 enlargement and an expanded upper extremity — so that it may rest on the ven- 

 tricular bands — is carried into place by an " introducer' ' and is guided by the left 

 forefinger of the surgeon, which is passed over the dorsum of the tongue to the 

 epiglottis and made to recognize the laryngeal opening. 



Thyrotomy is sometimes done for the removal of intralaryngeal tumors. The 

 incision extends from the thyro-hyoid space to the top of the cricoid cartilage, is 



