THE NERVES AND VESSELS OF THE LARYNX. 697 



NERVES. The nerves of the larynx are the superior and inferior Nerves are 

 aryngeal branches of the pneumo-gastric : the former is distributed fr" 001 ^ 8 - 

 o the mucous membrane, and the latter mostly to the muscles. 



The inferior lanjngeal nerve (recurrent), when about to enter the Recurrent 

 arynx, furnishes backwards an offset to the mucous membrane of ne 

 he pharynx ; this joins filaments of the upper laryngeal. The 

 lerve passes finally beneath the ala of the thyroid cartilage, and supplies 

 snds in branches for all the special muscles of the larynx, except muscled 

 he crico-thyroid. Its small muscular branches are mostly super- except one., 

 ficial, but that to the arytenoid muscle lies beneath the posterior 

 rico-arytenoid. Beneath the thyroid cartilage the inferior is joined 

 > v a long offset of the upper laryngeal nerve. 



The superior laryngeal nerve (internal division) pierces the thyro- Superior 

 hyoid membrane, and gives offsets to the mucous membrane of the JS" gea 

 )harynx ; it furnishes also a long branch beneath the ala of the 

 hyroid cartilage to communicate with the recurrent nerve. The joins recur- 

 rank terminates in many branches for the supply of the mucous rent> 

 nembrane : Some of these ascend in the aryteno-epiglottidean fold 

 ;o the epiglottis, and the root of the tongue. The others, which are and ends in 

 he largest, descend on the inner side of the sacculus, and supply membrane., 

 he lining membrane of the larynx as low as the true vocal cords. 

 One branch of this set pierces the arytenoid muscle, and ends in the 

 nucous membrane. 



The external branch of the superior laryngeal nerve has previously External 

 been traced to the crico-thyroid muscle (p. 634). S5ST* 1 



\ I>SELS. The arteries of the larynx are furnished from the Arteries: 

 superior and inferior thyroid branches. 



The laryngeal branch of the superior thyroid artery enters the superior 

 arynx with the superior laryngeal nerve, and divides into ascending ^^ 

 and descending branches ; some of these enter the muscles, but the superior 

 rest supply the epiglottis, and the mucous membrane from the root 

 of the tongue to the vocal cord. Like the nerves, the two laryngeal 

 arteries communicate beneath the ala of the thyroid cartilage, and 

 in the mucous membrane of the pharynx. 



The laryngeal branch of the ^inferior thyroid artery ascends on the inferior 

 back of the cricoid cartilage, and ends in the mucous membrane of fronUnlerior 

 the pharynx and the posterior muscles of the larynx. thyroid ; 



Si .me other twigs from the crico-thyroid branch of the superior from crico- 

 thyrrjid artery perforate the crico-thyroid membrane, and ramify in artery? 

 the mucous lining of the interior of the larynx at the lower part. 



Laryngeal veins. The vein accompanying the branch of the Veins, 

 superior thyroid artery joins the internal jugular or the superior 

 thyroid vein, and the vein with the artery from the inferior thyroid 

 opens into the plexus of the inferior thyroid veins. 



The lymphatics of the larynx pass to the deep cervical glands. Lympiia. 



