1168 THE ORGANS OF VOICE AND RESPIRATION 



At the junction of the posterior quadrate portion with the rest of the cartilage 

 is a small round articular eminence, for articulation with the inferior cornu of the 

 thyroid cartilage. 



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

 uppermost ring of the trachea by fibrous membrane (Figs. 881 and 882). 



Its upper border is directed obliquely upward and backward, owing to the great 

 depth of the posterior surface. It gives attachment, in front, to thp mirlrMe 

 portion of the cricothyroid membrane; at the sides, to the lateral portion of the 

 same membrane and to the lateral Cricoarytenoid muscle; behind, it presents, in 

 the middle, a shallow notch, and on each side of this is a smooth, oval surface. 

 directed upward and outward, for articulation with the base of an a.ry^nni'rl 



The inner surface of the cricoid cartilage is smooth, and lined with mucous 

 membrane. 



The Arytenoid Cartilages (cartilagines arytenoideae) (Fig. 882) are two in number, 

 and situated at the upper border of the cricoid cartilage, at the back of the larynx 

 in the interval between the posterior borders of the alee of the thyroid cartilages. 

 Each cartilage is in form a three-sided pyramid, and presents for examination 

 three surfaces, a base, and an apex. 



The posterior surface is triangular, smooth, concave, and gives attachment to 

 the transverse portion of the Arytenoid muscle. 



The antero-external surface is somewhat convex and rough. It presents, near 

 its apex, a small elevation, the colliculus; from this a ridge (crista arcuata) passes 

 backward and then forward and downward into a sharp-pointed process, the 

 vocal process. This ridge separates a deep depression above, the fovea triangularis, 

 from a broader and shallower depression below, the fovea oblonga. A short dis- 

 tance above the base a small tubercle on the anterior border gives origin to the 

 ligament of the false vocal cord, the superior thyroarytenoid ligament. To the 

 outer pnrt of the ridge, as well as the surface above and below, is attached the 

 Thvroarytenoid muscle. 



The internal surface is narrow, smooth, and flattened, and forms the lateral 

 boundary of the respiratory part of the glottis. 



The base (basis) of each cartilage is broad, and presents a concave smooth 

 surface, for articulation with the cricoid cartilage. Two of its angles require 

 special mention: The external angle, w r hich is short, rounded, and prominent, 

 projects backward and outward, and is termed the muscular process (processus 

 muscularis), from receiving the insertion of the Posterior and Lateral crico- 

 arytenoid muscles. The anterior angle, also prominent, but more pointed, pro- 

 jects horizontally forward, and gives attachment to the inferior thyroarytenoid 

 ligament, the supporting ligament of the true vocal cord. This angle is called 

 the vocal process (processus vocalis). 



The apex of each cartilage is pointed, curved backward and inward, and sur- 

 mounted by a small conical, cartilaginous nodule, the corniculum laryngis, articu- 

 lated with or united to the arytenoid cartilage. 



The Cornicula Laryngis or Cartilages of Santorini (cartilagines corniculatae) (Figs. 

 882 and 888) are two small conical nodules, consisting of yellow elastic cartilage, 

 which articulate with the summits of the arytenoid cartilages and serve to pro- 

 long them backward and inward. They are situated in the posterior parts of the 

 arytenoepiglottic folds, and are sometimes united to the arytenoid cartilages. 



The Cuneiform Cartilages or Cartilages of Wrisberg (cartilagines cuneiformes) 

 (Figs. 882 and 887) are two small, elongated pieces of yellow elastic cartilage, 

 placed one on each side, in the arytenoepiglottic fold (plica aryepiglottica) (Fig. 

 SS7), where they give rise to small whitish elevations on the inner surface of the 

 mucous membrane, just in front of the arytenoid cartilages. 



