CAVITY OF THE LARYNX 



447 



spends with that of the true vocal cord. It is inserted into the outer surface of 

 the arytenoid cartilage below the processus muscularis. The muscle closes the 

 rima and slackens the vocal cords. With the arytenoideus transversus and crico- 

 arytenoideus lateralis it forms a sphincter which closes the entrance to the larynx. 



Cavity of the Larynx 



The cavity of the larynx (Cavum laryngis) is smaller than one would expect 

 from its external api)earance. On looking into it through the ])liaryngeal end two 

 folds are seen projecting from its lateral walls. These are termed the vocal cords, 

 and they divide the cavity into two portions. 



The aditus laryngis, or pharyngeal aperture, is a large, oblique, oval opening, 

 which faces forward and upward into the ventral part of the pharjaix. It is 

 bounded in front l)y the epiglottis, behind i)y the arytenoid cartilages, and 



Body of thyroid cartilage 



Wing of thyroid cartilage 



Vocal cords 



- Cuneiform process 



Vcnlricidar niuacle 

 Lateral ventricle 



— Laryngeal saccule 

 Vocal tnuscle 



Crico-arytenoideus posterior 

 muscle 



Fio. 356. — Section of Larynx of Horse. 

 The plane of the section is parallel with the vocal cords. 



laterally by the aryteno-epiglottic folds of mucous membrane (Plicae aryepi- 

 glotticse), which stretch between the edges of the epiglottis and the arytenoid 

 cartilages. 



The vestibule of the larynx (Vestibulum laryngis) is that part of the cavity 

 which extends from the aditus to the vocal cords. On its lateral walls are the false 

 vocal cords (Plicae ventriculares) , each of which consists of a fold of mucous mem- 

 brane covering the anterior part of the thyro-arytenoid ligament and the cuneiform 

 process. Between the false and true vocal cord there is a pocket-like depression 

 termed the lateral ventricle of the larynx (\'entriculus lateralis laryngis). This is 

 the entrance to the larjnigeal saccule (Appendix ventriculi laryngis), a cul-de-sac of 

 the mucous membrane which is about one inch (ca. 2 to 3 cm.) long and extends 

 upward and backward on the inner surface of the thyroid lamina. There is a 

 small middle ventricle (Ventriculus laryngis medianus) at the base of the 

 epiglottis. 



The middle, narrow part of the cavity is termed the glottis or rima glottidis.^ 



1 The term glottis is commonly used to designate the interval between the vocal bands and 

 arytenoid cartilages or the structures that inclose that space. 



