522 



RESPIRATORY SYSTEM OF THE HORSE 



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 ventricular ligament and the cuneiform process. Between the 

 false and true vocal cord there is a pocket-like depression termed the lateral ven- 

 tricle of the larjTix (Ventriculus lateralis laryngis). This is the entrance to the 

 laryngeal saccule (Sacculus laryngis), a cul-de-sac of the mucous membrane which 

 is an inch or more (ca. 2.5 to 3 cm.) long and extends upward and backward on the 

 medial surface of the thyroid lamina. There is a small middle ventricle (Ventric- 

 ulus laryngis medianus) at the base of the epiglottis. 



The term "laryngeal saccule" seems decidedly preferable to the "appendix ventriculi lar- 

 yngis" of the B. N. A. The saccule is in relation with the ventricular and vocal muscles, and 



Lamina 



of thyroid 



cartilage 



Vocal 

 cords 



Body of thyroid 

 cartilage 



Cuneiform 

 ■process 



Ventricularis 



muscle 

 Lateral 

 ventricle 



Laryngeal 

 saccule 



Vocalis 

 muscle 



Crico- 



arytenoideus 

 dorsalis 

 muscle 



Fig. 466. — Cast of Right Lateral Ventricle 



AND Saccule of Horse; Medial View. 



1, Ventricle; 2, saccule. Figure is a little less than 



three-fourths of natural size. 



Fig. 46.5. — Section of Larynx of Horse. 

 The section cut is parallel with the vocal cords. 



Fig. 467. — Cast of Left Lateral Ventricle and 



Saccule of Larynx of Horse ; Lateral View. 

 1, Ventricle; 2, saccule; 3, impression of ventricu- 

 laris muscle; 4, impression of vocalis muscle. 



when the latter are atrophic (as in hemiplegia laryngis or "roaring"), the pouch is considerably 

 larger on the affected side, having occupied the space vacated by the muscles. The blind end of 

 the saccule lies just below the level of the muscular process of the arytenoid cartilage. It is loosely 

 attached to the contiguous structures. The average capacity of the saccule is about 5 to 6 e.c. 



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

 It is bounded on either side by the true vocal cord and the medial surface of the ary- 

 tenoid cartilage. The true vocal cords (Labia vocales) are situated behind the 

 false cords and the lateral ventricles. They extend from the angle of junction of 

 the body and laminse of the thyroid cartilage to the vocal processes of the arytenoid 

 cartilages. They are prismatic in cross-section, and their free edges look forward 

 and somewhat upward. The mucous membrane of the cord (Plica vocalis) is very 

 thin and smooth, and is intimately attached to the underlying vocal ligament. In 



