CHAPTER XXI 

 THE LARYNX VOICE AND SPEECH 



THF. voice is produced in the larynx by the vibrations of the 

 edge of two folds of the mucous membrane lining it. These 

 folds are called vocal cords. Their vibration is caused by 

 a blast of air driven out between them. 



Obtain the larynx of a sheep from a butcher. You will 

 notice at once the large open tube, the trachea, passing out 

 from it below, covered at the sides and in front by muscles and 

 fat. Above the trachea and to the front is the prominent 

 angle of the largest cartilage of the larynx. It is this that 

 forms the projection, popularly known as Adam's apple, which 

 is very marked in the neck of some persons. This will be 

 covered with muscles passing downwards by the side of the 

 trachea and upwards to an arch of bone, the hyoid bone, 

 which you can feel in the mass of tissue above. The hyoid 

 bone forms an arch of bone in front but is incomplete behind. 

 Muscles pass from it above into the tongue. 



The larynx is somewhat flat behind, and closely adhering 

 to it is the oesophagus, a collapsed muscular tube. Find the 

 lower cut end of this, and then with scissors cut it open to 

 the top. The cavity you have then laid open is wider above 

 than below ; this upper part is the pharynx. Notice the 

 smooth whitish mucous membrane lining the pharynx and 

 oesophagus. Projecting backwards into the pharynx from its 

 front wall is the prominent, almost erect cartilage, the epiglottis. 

 Immediately below this is the opening into the larynx, the 

 glottis, which is guarded also by two cushions of cartilage, 

 covered of course by the lining mucous membrane. Press 

 down the tip of the epiglottis and notice that it completely 



