702 



DISSECTION OF THE LARYNX. 



and lateral 

 parts ; 



relations. 



Crico- 

 thyroid 

 joint : 



movements. 



Crico- 

 arytenoid 

 joint and 

 ligament : 



movements, 



gliding 

 and 



rotation. 



Arytenoid 



and 



capitulum. 



above to the lower border of the thyroid cartilage (see fig. 212, p. ~>87). 

 The lateral part is thinner, and is continued upwards beneath the ala 

 of the thyroid cartilage, to end in a thickened border, which is attached 

 behind to the vocal process of the arytenoid cartilage, constituting the 

 inferior thyro-arytenoid ligament in the true vocal cord. 



The central part of the membrane is partly exposed between the 

 crico-thyroid muscles, and small apertures exist in it for the passage 

 of vessels into the larynx. The lateral 

 part is separated from thyroid cartilage 

 by the thyro-arytenoid and lateral crico- 

 arytenoid muscles. The deep surface oi 

 the membrane is lined by the mucous 

 membrane. 



The crico-thyroid articulation is formed 

 between the inferior cornu of the thyroid 

 and the lateral articular facet of the 

 cricoid cartilage. A capsular ligament, 

 which is thickest behind, and linec 

 by synovial membrane, surrounds the 

 articulation. 



This joint allows of a slight degree o 

 gliding movement backwards and for- 

 wards, and of a rotatory movemen 

 around a transverse axi?, by which the 

 front of the cricoid cartilage is raisec 

 or depressed. 



Crico- arytenoid articulation. Between 

 the cricoid and arytenoid cartilages there 

 is a synovial joint surrounded by a loose 

 capsule. To the inner side of the joint 

 there is a well marked crico-arytenoid 

 ligament, which passes from the upper 

 border of the cricoid cartilage near the 

 middle line to the adjacent part of the 

 base of the arytenoid and prevents the 

 latter cartilage being drawn forwards 

 over the cricoid. 



The arytenoid cartilage glides upwards 

 and inwards, or downwards and out- 

 wards, to a slight extent on the oblique 

 articular facet of the cricoid ; but its prin- 

 cipal movement is one of rotation, by which the vocal process is carried 

 inwards and somewhat downwards, approximating the vocal cords and 

 narrowing the glottis, or outwards and upwards, enlarging the glottis. 

 Between the apex of the arytenoid cartilage and the capitulum 

 there is sometimes a synovial joint, but the two cartilages are most 

 frequently united by connective or fibro- cartilaginous tissue. 



The thyro-arytt-noiil ligaments have been examined with the vocal 

 cords (pp. 695 and 696). 



FIG. 249. VIEW OF THE 

 VOCAL CORDS AND CRICO- 

 THYROID LIGAMENTS. 



1. True vocal cord. 



2. Posterior crico-arytenoid 

 muscle. 



3. Cricoid cartilage. 



4. Arytenoid cartilage. 



5. Sacculus laryngis. 



6. Lateral part of the crico- 

 thyroid membrane. 



