DISSECTION OF THE LARYNX. 



237 



The Superior Laryngeal Nerve has its origin described at page 199. 

 It gives motor filaments to the crico-thyroid and crico-pharyngeus 

 muscles ; and then, penetrating the 

 thyroid wing by the foramen near 

 its supero-posterior angle, the nerve 

 splits into sensory branches distrib- 

 uted to the mucous membrane of 

 the larynx, giving also twigs to the 

 lining of the pharynx and oeso- 

 phagus. 



The Inferior Laryngeal (Recur- 

 rent) Nerve has its origin and 

 course described at page 153. It is 

 the motor nerve to all the intrinsic 

 muscles except the crico - thyroid, 

 and it also gives some sensory twigs 

 to the laryngeal mucous membrane. 



INTERIOR OF THE LARYNX. 



Directions. — A vertical incision 

 should be made along the middle 

 line of the larynx behind, severing 

 the arytenoideus muscle and the 

 bezel of the cricoid cartilage. By 

 separating the lips of this incision, 

 a view of the interior of the larynx 

 from behind will be obtained, and 

 this is to be supplemented by look- 

 ing into the tube from its upper 

 and lower apertures. 



The Superior Aperture of the larynx is a large orifice placed at 

 the floor of the pharynx. It is bounded in front by the epiglottis, 

 behind by the pitcher -like lip of the arytenoid cartilages and the 

 fold of mucous membrane uniting them, and laterally by the aryteno- 

 epiglottic fold of mucous membrane. During deglutition the epiglottis 

 is folded over the aperture, which it closes like a lid. 



The Lower Aperture is circumscribed by the inferior edge of the 

 cricoid cartilage, and is directly continued by the lumen of the 

 trachea. 



The Glottis, or Rima Glottidis. This is a third aperture, placed about 

 the middle of the tube of the larynx, which it divides into an upper and 

 a lower compartment. In its anterior two-thirds this opening lies 

 between the right and left vocal cords, and in its posterior third it 



Fig. 32. 



Larynx, Back View. 



1. Epiglottis; 2. Arytenoid Cartilage ; 3. 

 Thyroid Cartilage ; 4. Arytenoideus ; 5. Crico- 

 Arytenoideus-Posticus ; 6. Cricoid Cartilage ; 

 7. 1st Ring of Trachea ; S. Thyroid Body. 



