CAVITY OF THE LARYNX 



521 



The ventricularis rotates the arytenoid so as to bring the apical part of the cartilage down- 

 ward and forward. 



In some cases there is a small thyro-arytenoideus extemus muscle which arises from the 

 medial face of the lamma of the thyroid cartilage near the dorsal border, passes upward and 

 backward, and blends with the arytenoideus transversus. 



CAVITSr OF THE LARYNX 



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

 expect from its external appearance. On looking into it through the pharyngeal 

 end two folds are seen projecting from each lateral wall. These are termed the 





Fig. 464. — Paht of Sagittal Section of Head of Horse. 

 Section is cut just to left of median plane. 

 1, Epiglottis; 2, body of thyroid cartilage; 3, arytenoid cartilage; 4, 4', lamina and arch of cricoid cartilage; 5, 

 ary-epiglottic fold; 6, vocal cord (labium vocale) ; 7, ventricular fold or false vocal cord (plica ventricularisj ; S, lateral 

 ventricle of larynx; 8', dotted line indicating contour of laryngeal saccule; 9, middle ventricle of larynx; 10, m. crico- 

 arytenoideus dorsalis; H, oesophagus; 12, septum of areolar tissue between guttural pouches; 13, m. rectus capitis 

 ventralis; 14, l^dy of sphenoid bone; 15, pharyngeal recess; 16, arrow points into nasal cavity; 17, pharj'ngeal open- 

 ing of auditive or Eustachian tube; IS, posterior pillars of soft palate united over aditus oesophagi; 19, arrow points 

 into vestibule of larynx; 20, soft palate; 21, tonsil; 22, root of tongue; 23, m. hyo-epiglotticus ; 24, hyoid bone; 25, 

 mandibular lymph glands; 26, mm. omo-hyoideus and sterno-hyoideus ; A, vestibule of larynx; B, glottis; C, post- 

 glottic part of larynx; D, trachea; E, pharynx, F, isthmus faucium. 



vocal corclSj and the narrow part of the cavity between them is the rima glottidis. 

 Thus it is convenient to recognize three divisions of the cavity. 



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

 which faces into the ventral part of the pharynx. It is bounded in front by the 

 epiglottis, behind by the arytenoid cartilages, and laterall}^ by the aryteno-epi- 

 glottic folds of mucous membrane (Plicae aryepiglotticte), which stretch between 

 the edges of the epiglottis and the arytenoid cartilages. 



