234 THE RESPIRATORY APPARATUS 



cavities is warmed by coming in contact with the 

 highly vascularized mucous membrane lining them, 

 and thus is prevented from reaching the lungs at a 

 low temperature, which would cause their congestion 

 and be dangerous to health. The air also passes 

 through the pharynx to reach the larynx. 



The Larynx. The larynx is the organ of the voice, 

 and is placed at the upper and forepart of the neck, 

 between the trachea and base of the tongue. It com- 

 municates above with the laryngopharynx, below with 

 the trachea. 



Relations. It has on each side of it the carotid vessels, 

 and behind it the pharynx. In front are the pretra- 

 cheal portions of the cervical fascia and the upper end 

 of the thyroid gland, and on each side the sterno- 

 hyoid and thyroid and the thyrohyoid muscles. It 

 consists of various cartilages held together by liga- 

 ments, and is lined internally by mucous membrane, 

 continuous with that of the pharynx above and the 

 trachea below. 



The cartilages are nine: Three pairs, the arytenoid, 

 cornicula laryngis, and cuneiform; and three single, 

 the thyroid, cricoid, and epiglottis. 



The thyroid cartilage is the largest, and consists of 

 two lateral parts or alse uniting in front to form the 

 projection of the Adam's apple (pomum Adami). 

 This is subcutaneous, more distinct above and in the 

 male. Internally it is smooth, and in the angle the 

 epiglottis, true and false vocal cords, and the thyro- 

 arytenoid and thyro-epiglottidean muscles are attached. 

 The upper border is concavoconvex, and in front is 

 notched over the pomum Adami, giving attachment 

 throughout to the thyrohyoid membrane. The lower 

 border is joined to the cricoid cartilage by the middle 

 portion of the cricothyroid membrane; and on either 

 side, affords attachment to the cricothyroid muscle. 

 The posterior borders end in the upper and lower 

 cornua (horns); to the upper are attached the lateral 



