332 THE RESPIRATORY SYSTEM 



and very slightly upwards towards the laryngeal part of the 

 pharynx (Fig. 117). The direction of this opening must be 

 borne in mind when an intubation tube is being inserted into 

 the larynx. The index finger of the left hand is introduced 

 into the mouth and is carried backwards over the tongue until 

 the upper border of the epiglottis is reached. The intubation 

 tube is then passed in with the right hand and guided along 

 the left index finger. The posterior or laryngeal surface of the 

 epiglottis slopes obliquely forwards and downwards, and the 

 end of the tube is kept in contact with this surface until it 

 enters the upper compartment of the larynx. 



The upper aperture of the larynx is bounded laterally 

 by the ary-epiglottic folds (Fig. 86). They contain the 

 ary-epiglottic muscles, which act as a sphincter of the opening 

 during deglutition. On laryngoscopic examination, two little 

 elevations, separated by a small groove, can be observed 

 in the posterior part of the fold. They are produced 

 by nodules of cartilage which lie in the submucous tissue. 

 The more posterior nodule, which is situated on the apex 

 of the arytaenoid, is termed the corniculate cartilage, and 

 the more anterior the cuneiform cartilage. Occasionally, in 

 tuberculous laryngitis, these elevations become abnormally 

 enlarged and they may hide the interior of the larynx on 

 laryngoscopic examination. 



On the lateral side of the ary-epiglottic fold there is a 

 small recess, termed the recessus piriformis. The mucous 

 membrane which lines it is supplied with sensation by the 

 internal laryngeal nerve, and when small particles of food 

 become lodged in the recess, they set up an uncontrollable fit 

 of coughing (p. 97). 



The vestibule of the larynx extends from the aditus to the 

 ventricular folds (false vocal cords), and, owing to the 

 direction of the aditus, its anterior wall is much longer than 

 its posterior wall. The anterior wall is formed by the epiglottis, 

 which shows, in its lower part, a well-marked convex pro- 

 minence, termed the epiglottic tubercle (cushion). 



