THE HEAD AND NECK. 



109 



External angle for insertion of posterior and lateral crico-arytenoid muscles. 

 The intrinsic muscles are as follows : 



1. The thyro-arytenoideus. (Fig. 70.) 



2. The crico-arytenoideus lateralis. (Fig. 70.) 



3. The crico-arytenoideus posticus. (Fig. 69.) 



4. The arytenoideus. (Fig. 69.) 



5. The crico-thyroid. (Fig. 27.) 



The intrinsic muscles and the mucous membrane are supplied by (i) the 

 superior laryngcal branch of the pneumogastric ; (2) the inferior laryngeal 

 branch of the pneumogastric ; (3) the sympathetic nerves accompanying the 

 superior and inferior laryngeal arteries ; they take the name of the arteries. 



The superior laryngeal nerve (Fig. 71) supplies the mucous membrane and 

 the crico-thyroid muscle. 



Epiglottis 



Cut edge of hyo-epiglottidean 



ligament 



SECTION THROUGH BODY OF HYOID 

 BONE 



Peri glottis 



Cut edge of thyro-hyoid 

 membrane 



Thyro-epiglottideus muscle 



SECTION OF THYROID CARTILAGE 

 Thyro-arytenoideuB muscle 



Crioo - arytenoideua lateralis 

 muscle (the pointer crosses 

 erieo-thyroid membrane) 



CRICOID CARTILAGE 



Aryteno-epiglottidean fold 

 Aryteno-epiglottideus muscle 



Arytenoideus muscle 



Crleo-arytenoideus postious 



Recurrent laryngeal nerve 



FIG. 72. SIDE VIEW OF THE MUSCLES AND LIGAMENTS OF THE LARYNX. 



The inferior laryngeal supplies the remaining muscles. 



The false vocal cord extends from the retiring angle of the thyroid cartilage 

 (Fig. 69) to the anterior surface of the arytenoid cartilage. (Fig. 70.) 



The true vocal cord extends from the retiring angle of the thyroid cartilage 

 (Fig. 69) to the anterior angle of the arytenoid cartilage. (Fig. 70.) 



The chink, or rima glottidis, is the space between the two true vocal cords. 

 This chink consists of two parts a respiratory or posterior and a vocalizing or 

 anterior. 



The thyro-arytenoid muscle (Fig. 69) extends from the retiring angle of 

 the thyroid cartilage to the anterior surface of the arytenoid cartilage. (Fig. 70.) 

 The action of this muscle is to pull the arytenoid cartilage forward and thereby 

 relax the vocal cords. 



The arytenoid muscle (Fig. 71) extends from the posterior surface of one 



