LIGAMENTS OF LARYNX. 



161 



Fig. 44. 



respiration it is placed vertically, but during deglutition it takes a hori- 

 zontal direction so as to close the opening of the larynx. 



The anterior surface is bent forwards to the tongue, to which it is con- 

 nected by three folds of mucous membrane ; and the posterior surface, 

 hollowed laterally, is convex from above down. To its sides the arytseno- 

 epiglottid folds of mucous membrane are united. After the mucous mem- 

 brane has been removed from the epiglottis its substance will be seen to 

 be perforated by numerous spaces, which lodge mucous glands. 



Between the epiglottis and the hyoid bone is a mass of yellowish fat 

 with some glands; this has been sometimes called the epiglottidean gland. 



LIGAMENTS OF THE LARYXX. The larynx is connected by extrinsic 

 ligaments with the hyoid bone above and the trachea below. Other liga- 

 ments join together the cartilages, forming joints in some cases. 



Union of the larynx with the hyoid bone and the trachea. A thin loose 

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

 hyoid bone ; and a second membrane connects 

 the cricoid cartilage with the trachea. 



The thyro-hyoid ligament (fig. 42, L) is at- 

 tached on the one part to the upper border of the 

 thyroid cartilage; and on the other, to the upper 

 border of the hyoid bone, at the posterior aspect. 

 Of some thickness in the centre, it gradually be- 

 comes thinner towards the sides; and it ends 

 laterally in a rounded elastic cord, which inter- 

 venes between the extremity of the hyoid bone 

 and the upper cornu of the thyroid cartilage. 



The superior laryngeal nerve and vessels per- 

 forate the ligament, and a synovial membrane is 

 placed between it and the posterior surface of the 

 hyoid bone. In the elastic lateral part of the 

 ligament will be found occasionally a small ossific 

 nodule (cartilago triticea). 



The membrane joining the lower border of the 

 cricoid cartilage to the first ring of the trachea 

 crico-tracheal ligament, resembles the band 

 joining the rings of the trachea to each other. 



Union of the cricoid and thyroid cartilages. 

 These cartilages are joined in the middle line in 

 front by ligament; and on the side, by a joint 

 with the small cornu ot the thyroid cartilage. 



The crico-thyroid ligament or membrane (fig. 

 44, 6 ) closes the space between the thyroid, cri- 

 coid, and arytsenoid cartilages, and the right half 

 is now visible. It is yellow in color, and is 

 formed mostly of elastic tissue. At the centre it 

 is thick and strong, but is thinner on each side 

 as it is continued backwards. By the lower bor- 

 der it is fixed to the upper edge of the cricoid as 

 far back on each side as the joint with the arytaenoid cartilage. Its upper 

 border, free and rounded, is covered by mucous membrane, and forms the 

 lower vocal cord. In front it is united to the thyroid cartilage ; and be- 

 hind to the base of the arytajnoid. 

 11 



VIEW or THE VOCAL CORDS 

 AND CRICO-THYROID LIGA- 

 MENTS. 



1. True vocal cord. 



2. Post, crico-arytsen muscle. 



3. Cricoid cartilage. 



4. Arytsenoid cartilage. 



5. Sacculus laryn'gis. 



6. Crico-thyroid membrane. 



