574 



TEXT-BOOK OF PHYSIOLOGY. 



while the narrow circular portion is directed forward. It rests upon 

 the upper ring of the trachea, to which it is firmly attached by 

 fibrous tissue. The posterior upper border of the quadrate portion 

 presents on either side an oval convex facet for articulation with the 

 arytenoid cartilage. The long axis of this facet is directed down- 

 ward, outward, and forward. 



10. 



FIG. 261. LARYNGEAL CARTILAGES AND 

 LIGAMENTS, ANTERIOR SURFACE. 

 i. Hyoid bone. 2, 2, 3, 3. Greater 

 and lesser cornua. 4. Thyroid 

 cartilage. 5. Thyro-hyoid mem- 

 brane. 6. Thyro-hyoid ligaments. 

 7. Cartilaginous nodule. 8. Cri- 

 coid cartilage. 9. The crico-thyroid 

 membrane. 10. The crico-thyroid 

 ligaments. n. Trachea. (Sap- 

 pey.} 



FIG. 262. LARYNGEAL CARTILAGES 

 AND LIGAMENTS. POSTERIOR SUR- 

 FACE, i, i. Thyroid cartilage. 2. 

 Cricoid cartilage. '3, 3. Arytenoid 

 cartilages. 4, 4. Crico-arytenoid 

 articulations. 5, 5. Crico-thyroid 

 articulations. 6. Union of the 

 cricoid cartilage and of the trachea. 

 7. Epiglottis. 8. Ligament uniting 

 - it to the reentering angle of the 

 thyroid cartilage. (Sappey.} 



The thyroid, the largest of the laryngeal cartilages, is composed 

 of two flat quadrilateral plates, united anteriorly, at an angle of 

 about 90 degrees. Each plate is directed backward and outward 

 and terminates in a free border, which is prolonged upward and 

 downward for some distance, terminating in two processes, the 

 superior and inferior cornua. The upper border of the thyroid is 

 deeply notched in front. The inferior border overlaps laterally 

 the cricoid. 



