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 externus muscle which arises from the 
medial face of the lamina of the thyroid cartilage near the dorsal border, passes upward and 
backward, and blends with the arytenoideus transversus. 
CAVITY 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 
Fic. 464.—Part or Sacitrat Section oF Heap or 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 ventricularis); 8, lateral 
ventricle of larynx; 8’, dotted line indicating contour of laryngeal saccule; 9, middle ventricle of larynx; 10, m. crico- 
arytenoideus dorsalis; 11, cesophagus; 
ventralis; 14, body of sphenoid bone; 15, pharyngeal recess; 
12, septum of areolar tissue between guttural pouches; 13, m. rectus capitis 
16, arrow points into nasal cavity; 17, pharyngeal open- 
ing of auditive or Eustachian tube; 18, posterior pillars of soft palate united over aditus cesophagi; 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; EZ, pharynx, F, isthmus faucium. 
vocal cords, 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 laterally by the aryteno-epi- 
glottic folds of mucous membrane (Plice aryepiglotticee), which stretch between 
the edges of the epiglottis and the arytenoid cartilages. 
