VOCAL AND RESPIRATORY APPARATUS. 



THE LARYNX is a musculo-cartilaginous box at the top of the 

 trachea, below the root of the tongue and the hyoid bone, and is 

 the organ of the voice. It is composed of cartilages connected 

 by ligaments, provided with muscles, blood-vessels, and nerves, 

 and lined with mucous membrane. The cartilages are nine in 

 number, three single and three pairs: 



Thyroid, 



Cricoid, 



Epiglottis, 



Two arytenoid, 



Two cornicula laryngis, 



Two cuneiform. 



The thyroid, the largest cartilage, consists of two quadri- 

 lateral halves, united in front in the median line, or entering 

 angle of the thyroid, the upper part of which is the pomum 

 adami. The outer surface is marked by an oblique ridge for the 

 attachment of muscles. The inner surface is smooth and cov- 

 ered by mucous membrane, and has in front attached the true 

 and false vocal cords. The posterior angles are prolonged into 

 superior and inferior horns, the superior giving attachment to 

 the thyro-hyoid ligament, the inferior articulating with the 

 sides of the cricoid cartilage. 



The cricoid cartilage resembles a seal ring, narrow in front, 

 the back part of the upper border articulates with the arytenoid 

 cartilage, and on each side externally are two facets for the 

 articulation of the inferior horns of the thyroid. 



The epiglottis is a spoon-shaped, fibro-cartilaginous plate, 

 large above, its narrow inferior extremity is prolonged and 

 attached by a band of fibre-elastic tissue of thyro-epiglottic liga- 

 ment to the thyroid cartilage. It is also attached to the posterior 

 surface of the hyoid bone by the Ivyo-epiglottic ligament. The 

 anterior or lingual surface has three reflections of mucous mem- 

 brane between it and the tongue, called the glosso-epiglottidean 

 ligaments. 



The arytenoid cartilages each resembles the mouth of a 

 pitcher, from which they are named. They are smaller than 

 the other two, and are situated on the summit of the cricoid 

 cartilage posteriorly. They are three-sided, the apex extends 

 backward, and is surmounted by the sujmi-arytenoid, cornicula 

 laryngis, or cartilages of Santorini. 



(246) 



