THE LARYNX 405 



cartilages outward around a vertical axis passing through the 

 cricoarytenoid articulations, so that their vocal processes and 

 cords attached to them become widely separated. The lateral 

 cricoarytenoids by rotating the arytenoid cartilages inward, 

 close the glottis, and so approximate their vocal processes. 

 The arytenoids approximate the arytenoid cartilages, and 

 thus closes the opening of the glottis, particularly at its back 

 part. The action of the cricothyroids is to raise the anterior 

 portion of cricoid cartilage while the extrinsic muscles fix 

 the thyroid cartilage this action depresses the back of the 

 cricoid cartilage, carrying downward the arytenoid cartilages 

 with it, and thus produce tension and elongation of the vocal 

 cords. 



The thyroarytenoid shorten the vocal cords by drawing 

 forward the arytenoid cartilages toward the thyroid cartilage. 

 But, owing to the connection of the internal portion with the 

 vocal cord, this part, if acting separately, is supposed to modify 

 its elasticity and tension, and the outer portion being inserted 

 into the outer part of the anterior surface of the arytenoid 

 cartilage, may rotate it inward, and thus narrow the rima 

 glottidis by bringing the two cords together. (Gray.) 



The vessels of the larynx are derived from the superior 

 laryngeal artery a branch of the superior thyroid artery, and 

 the inferior laryngeal artery, a branch of the inferior thyroid 

 artery. The veins are the superior thyroid, which empties 

 into the internal jugular vein, and the inferior thyroid, which 

 empties into the left innominate vein. The lymphatics of 

 the larynx are divided into superior and inferior set. The 

 superior accompany the superior laryngeal artery, pierce the 

 thyroliyoid membrane and pass the nodes located at the bifurca- 

 tion of the common carotid artery; the inferior empty into 

 the deep cervical nodes, a node anterior to the cricothyroid 

 membrane, and the nodes along the inferior thyroid artery. 

 The nerves are the internal and external branches of the superior 

 laryngeal (a branch of the pneumogastric), the inferior or 

 recurrent laryngeal, a branch of pneumogastric, and sympathetic 

 filaments, which accompany the laryngeal nerves. The internal 

 branch of the superior laryngeal supply the mucous membrane, 

 the external branch of the superior laryngeal innervates the 

 cricothyroid muscle. The inferior or recurrent laryngeal 

 nerve innervates all the intrinsic muscles of the larynx except 

 the cricothyroid and a portion of the arytenoid. 



