LIGAMENTS OF THE LARYNX. 701 



ligament. The posterior surface is entirely covered by closely and 

 adherent mucous membrane, and is for the most part concave ; but pos1 

 at the lower end there is an elevation known as the tubercle or 



tfiion of the epiglottis. To the sides the aryteno-epiglottidean folds sides; 

 of mucous membrane are united. After the mucous membrane has glands in it. 

 been removed from the cartilage, its substance will be seen to be 

 excavated by numerous pits, which lodge mucous glands. 



In the adult the hyaline cartilages of the larynx are commonly ossification 

 to a greater or less extent (in old persons sometimes completely) 

 converted into bone. The ossification begins in the thyroid and 

 cricoid cartilages at about twenty years of age, the deposition of 

 osseous matter in the former taking place first in the neighbourhood 

 of the inferior cornu, and thence extending along the inferior and 

 posterior borders; while in the cricoid two or three bony spots 

 appear near the arytenoid articular surface on each side, and spread 

 through the upper part of the cartilage. The arytenoid cartilages 

 ossify later, from below upwards. The tendency to ossification is 

 more marked in the male than in the female. 



LIGAMENTS or THE LARYNX. The larynx is connected by extrinsic Ligaments 

 Ligaments with the hyoid bone above and the trachea below. Other 

 ligaments unite together the cartilages, sometimes with joints. 



Union of tht larynx with the hyoid bone and tJie trachea. A loose To hyoid 

 elastic membrane (thyro-hyoid) extends from the thyroid cartilage to 

 the hyoid bone ; and a second membrane connects the cricoid cartilage 

 with the trachea. 



The thyro-hyoid membrane (fig. 247, L, p. 695) is attached on the one Thyro-hyoid 

 land to the upper border of the thyroid cartilage ; and on the other membrane: 

 to the upper border of the hyoid bone. Its central part, extending 

 from the body of the hyoid bone to the margins of the notch in the median and 

 ;hyroid cartilage, is of some thickness, but its lateral parts are thin rts! 

 and ill-defined. It ends behind in a rounded elastic cord on each 

 side (lateral thyro-hyoid ligament), uniting the extremity of the 

 great cornu of the hyoid bone to the superior cornu of the thyroid thyro-hyoid 

 cartilage : this band frequently contains a small cartilaginous or J,^* 611 * 

 osseous nodule (cartilage triticea). contains 



The superior lary ngeal nerve and vessels perforate the lateral part 

 of the membrane : and a synovial bursa is placed between its central 

 :>art and the posterior surface of the body of the hyoid bone. 



The membrane joining the lower border of the cricoid cartilage Crico- 

 to the first ring of the trachea, crico-tracheal ligament, resembles membrane, 

 the fibrous layer joining the rings of the trachea to the other. 



Union of the cricoid and thyroid cartilages. These cartilages are 

 united by a membrane in front, and a synovial joint on each side. 



The crico -thyroid membrane (fig. 249, 6 ) occupies the space Crico- 

 between the thyroid, cricoid, and arytenoid cartilages ; and its right membrane : 

 half is now visible. It is of a yellow colour and is formed mainly of 

 elastic tissue. By its lower border the membrane is fixed to the upper 

 edge of the cricoid cartilage, reaching back to the articulation with 

 the arytenoid. Its central part is thick and strong, and is attached median part, 



