70 ANATOMY OF THE HEAD AND NECK. 



glottis, backward, downward, and inward, in a semi-circular 

 form, toward each other. In these folds, posteriorly, are 

 found the cartilages of Wrisberg, and the cartilages of 

 Santorini. 



The larynx is supplied with nerves from the superior and 

 inferior laryngeal branches of the pneuinogastric nerve. 

 The superior laryngeal penetrates the thyro-hyoid mem- 

 brane, and supplies the mucous membrane and crico-thyroid 

 muscle. The inferior or recurrent laryngeal nerve passes 

 beneath the ala of the thyroid cartilage, and supplies all the 

 special muscles of the larynx except the crico-thyroid. 



These nerves are accompanied by the laryngeal branches 

 of the superior and inferior thyroid arteries, which follow 

 them in their distribution to the mucous membrane and 

 muscles. 



The hyoid bone and the cartilages of the larynx are now to be de- 

 nuded, care being taken to leave the ligaments which unite the dif- 

 ferent cartilages, as well as the membrane between the larynx and 

 hyoid bone. 



The HYOID BONE consists of a body and four cornua, two 

 greater and two lesser. The greater cornu extends back- 

 ward, decreasing gradually in size, and ends posteriorly in 

 a tubercle ; the lesser cornu is directed upward, and is 

 about the size and shape of a kernel of rice ; it marks the 

 union of the body of the bone with the greater cornu, and 

 is seldom co-ossified with it; the stylo-hyoid ligament is 

 attached to it. (p. 51.) 



The THYROID CARTILAGE of the larynx consists of two 

 quadrilateral halves united anteriorly at an acute angle, 

 forming a projection called the pomum Adami. The upper 

 border, above the pomum Adami has a deep notch called 

 incisura thyroidese superior; the lower border has a 

 slighter notch called incisura thyroidese inferior. Poste- 

 riorly the cartilage has a thick border, which terminates 

 above and below in a cornu ; the upper being the longest, 

 and the lower the stoutest. The upper cornu is connected 

 to the greater cornu of the hyoid bone by a ligament, called 

 the thyro-hyoid; a sesamoid bone, or cartilage, is usually 

 found in it. The lower cornu articulates with the cricoid 

 cartilage. The inner surface of this cartilage is smooth, 

 the outer is marked by an oblique ridge, extending from its 

 upper cornu to the middle of the lower border. 



