28 



The Larynx 



of the arytaenoid. These muscles rotate the anterior angle 

 arytaenoids inwards, and thus approximate the cords. 



The thyro-aryteenoid runs along the outer side of the true vocal 

 cord, being attached to the retiring angle of the thyroid, and to the an- 

 terior surface of the arytsenoid. Contracting, it shortens and slackens 

 the cord ; it is the antagonist of the crico-thyroid. 



The arytaenoideus consists of bundles of striated fibres passing 

 from the back of one arytaenoid cartilage to the other. Its action is 

 to tilt the arytaenoid cartilages together and so to close the hinder 

 part of the glottis. It derives its motor filaments both from the 

 superior and the recurrent laryngeal branch of the vagus. 



All the muscles of the interior of the larynx can act together as a 

 sort of sphincter; and so it happens that when the epiglottis is 

 destroyed by ulceration the patient can swallow without being choked. 

 He is safest, however, when bending his head well down and sucking 



Vocal cord 

 Thyroid cart. 

 Cricoid cart. 



Glottis dilated. (HOLDEN.) 



up the food by a tube, when it is taken to the oesophagus in the 

 zealous grasp of the constrictors. 



Laryngismus stridulus (Xapuyyi^co, shout ; strideo, hiss] is a 

 spasmodic affection of the muscles of the cords in infancy ; it is also 

 called laryngeal asthma, and is often associated with spasmodic 

 contractions in the hands and feet. It is the result of some central 

 nervous irritation, and may be caused by indigestible food disturbing 

 the pneumogastric filaments in the stomach. Spasmodic asthma in 

 the adult may be caused by the pressure of aneurysmal or malignant 

 tumours upon the recurrent laryngeal nerves. The spasm generally 

 yields as carbonic acid poisoning comes on, but it may have to be 

 treated with chloroform inhalations, or, in the adult, by opening the 

 windpipe. 



The mucous membrane of the larynx is continuous with that of 

 the pharynx and of the trachea. It is covered with columnar ciliated 





