354 



COORDINATION AND SENSATION 



is made of cartilage. At the top it is partly encircled by 

 a small bone (the hyoid), and its opening into the pharynx 

 is guarded by a flexible lid, called the epiglottis. The 

 cartilage in its walls is in eight separate pieces, but the 

 greater portion of the structure is formed of two pieces 

 only. These are known as the thyroid cartilage and the 

 cricoid cartilage (Fig. 149). Both can be felt in the throat 

 the thyroid as the projection known as "Adam's apple," 

 and the cricoid as a broad ring just below. 



The thyroid cartilage consists of two V-shaped pieces, 

 one on either side of the larynx, meeting at their points 



A B 



FIG. 149. The larynx. A. Outside view. B. Vertical section 

 through larynx, showing inside. I. Thyroid cartilage. 2. Cricojd carti- 

 lage. 3. Trachea. 4. Hyoid bone. 5. Epiglottis. 6. Vocal cord. 

 7. False vocal cord. 8. Lining of mucous membrane. 



in front, and each terminating at the back in an upward 

 and a downward projection. Between the back portions 

 of the thyroid is a space equal to about one third of the 

 circumference of the larynx. This is occupied by the 

 greater portion of the cricoid cartilage. This cartilage 



