158 THE HEAD AND NECK 



during phonation. In quiet respiration the rima glottidis is 

 triangular with the apex in front, but in forced breathing it 

 becomes diamond-shaped owing to lateral rotation of the vocal 

 processes of the arytenoids. During high notes the vocal folds 

 become adducted, and only the posterior part of the glottis, 

 i.e. the part between the two arytenoids, remains open. A 

 yellowish elevation may be observed in the posterior part of 

 the vocal fold. It is due to the vocal process of the arytenoid. 

 In addition to the boundaries of the aperture and the interior 

 of the larynx, a good view may be obtained of the recessus 

 piriformis and the valleculse, and if the vocal folds are widely 

 abducted, the interior of the trachea may be examined. It 



Base of tongue 



Glosso- 



epiglottic 



fold 



Epiglottis 

 Tubercle- 

 Plica vocalis 



Cuneiform cartilage' 



Corniculate cartilage 



FIG. 49. The Larynx as seen in the living subject by means of the 

 Laryngoscope. 



must be remembered that irregular appearances may be caused 

 by the cicatricial contraction which commonly follows ulceration 

 in this region. 



Polypi and other growths, which may occur in relation to 

 the epiglottis, ary-epiglottic folds, ventricular and vocal folds, 

 may be removed via the mouth by the intralaryngeal method. 

 If this is not possible, satisfactory access may be obtained by 

 sub-hyoid pharyngotomy (p. 159) or thyreotomy (p. 162). 



The lymph vessels of the larynx may be subdivided into a 

 supraglottic and an infraglottic group. They communicate 

 freely with one another in the posterior wall of the larynx, but 

 across the vocal folds the connections are few and irregular. 

 The supraglottic efferents follow the course of the internal laryn- 

 geal nerve (p. 159) and open into the upper anterior group of the 

 deep cervical lymph glands. The infraglottic efferents run 



