1074 



SPLANCHNOLOGY 



EPIGLOTTIS 



THYROID 



the middle line is connected to the cricoid cartilage by the middle cricothyroid 



ligament. 

 The posterior border, thick and rounded, receives the insertions of the Stylo- 



pharyngeus and Pharyngopalatinus. It ends above, in the superior cornu, and 



below, in the inferior cornu. The 

 superior cornu is long and narrow, 

 directed upward, backward, and 

 medialward, and ends in a conical 

 extremity, which gives attachment 

 to the lateral hyothyroid ligament. 

 The inferior cornu is short and thick; 

 it is directed downward, with a slight 

 inclination forward and medialward, 

 and presents, on the medial side of 

 its tip, a small oval articular facet 

 for articulation with the side of the 

 cricoid cartilage. 



During infancy the laminae of the 

 thyroid cartilage are joined to each 

 other by a narrow, lozenge-shaped 

 strip, named the intrathyroid cartil- 

 age. This strip extends from the 

 upper to the lower border of the 

 cartilage in the middle line, and is 

 distinguished from the laminae by 

 being more transparent and more 

 flexible. 



The Cricoid Cartilage (cartilago 

 cricoidea) is smaller, but thicker and 

 stronger than the thyroid, and forms 

 the lower and posterior parts of the 

 wall of the larynx. It consists of two 

 parts: a posterior quadrate lamina, 

 and a narrow anterior arch, one- 

 fourth or one-fifth of the depth of 

 the lamina. 



The lamina (lamina cartilaginis 

 cricoideas; posterior 'portion) is deep 

 and broad, and measures from above 

 downward about 2 or 3 cm.; on its 

 posterior surface, in the middle line, 

 is a vertical ridge to the lower part 

 of which are attached the longitu- 

 dinal fibers of the esophagus; and on either side of this a broad depression for the 



Cricoarytsenoideus posterior. 



The arch (arcus cartilaginis cricoidece; anterior portion) is narrow and convex, 



and measures vertically from 5 to 7 mm. ; it affords attachment externally in front 



and at the sides to the Cricothyreiodei, and behind, to part of the Constrictor 



pharyngis inferior. 



On either side, at the junction of the lamina with the arch, is a small round 



articular surface, for articulation with the inferior cornu of the thyroid cartilage. 

 The lower border of the cricoid cartilage is horizontal, and connected to the 



highest ring of the trachea by the cricotracheal ligament. 

 The upper border runs obliquely upward and backward, owing to the great 





Cuneiform cartilage 



Insertion of 



Cricoarytcenoideus 



posterior 



Posterior 

 surface 



Arytenoid cartilages, base 



CRICOID 



ArticiMar facet for 

 arytenoid cartilage 



Articular facet for 

 inferior cornu of 

 thyroid cartilage 



FIG. 950. The cartilages of the larynx. Posterior view. 



