CARTILAGES OF THE LARYNX 



515 



Cartilages of the Larynx 



There are three single cartilages and one pair; the single cartilages are the 

 cricoid, thyroid, and epiglottic; the arytenoid cartilages are paired. 



The cricoid cartilage (Cartilage cricoidea) is shaped like a signet ring. The 

 dorsal part is a broad, thick, quadrilateral plate termed the lamina; the external 

 (dorsal) surface of this is marked by a median ridge (Crista mediana) separating two 

 shallow cavities, from which the dorsal crico-arytenoid muscles arise. On either 

 side of these depressions are two articular facets. The anterior facet (Facies articu- 

 laris arytsenoidea) is at the anterior border, is oval and convex, and articulates 

 with the arytenoid cartilage. The posterior facet (Facies articularis thyreoidea) is 

 situated on the front of a ridge, a short distance from the posterior border; it is 

 concave, and articulates with the posterior cornu of the thyroid cartilage. The 

 ventral and lateral parts of the ring are formed by a curved band, called the arch 

 (Arcus), which is narrowest ventrally. The lateral surfaces of the arch are grooved 



Muscular process 



Apex 



Thyroid 

 ^. fissure Liileriil bonier 



Apex 



Crico-thyroid 

 membrane 



Laryngeal prominence 



Fig. 457.- 



-Laryngeal Cartilages and Part of Trachea of Horse; Bight View. 

 For "thyroid wing" read "thyroid lamina." 



for the crico-thyroid muscle. The anterior border of the lamina is thick and 

 slightly concave; the posterior border is thin and irregular. The anterior border 

 of the arch is concave ventrally and gives attachment to the crico-thyroid membrane ; 

 laterally it is thicker and gives attachment to the crico-arytenoideus lateralis 

 muscle. The posterior border of the cartilage is attached to the first ring of the 

 trachea by the crico-tracheal membrane. The internal surface is smooth and is 

 covered with mucous membrane. 



The thyroid cartilage (Cartilago thyreoidea) consists of a median thickened 

 portion, termed the body, and two lateral lamina;. The body forms ventrally a 

 slight prominence (Prominentia laryngea), which can be felt, but is not visible m 

 the living subject; it is related dorsally to the base of the epiglottis, which is at- 

 tached to it by an elastic ligament. The laminae or wings spring from the body 

 on either side and form a large part of the lateral wall of the larynx. _ Each is a 

 rhomboid plate, presenting a slightly convex lateral surface, which is divided into 

 two areas by an oblique line (Linea obliqua), on which the thyro-hyoid and thyro- 

 pharyngeus muscles meet. "The dorsal border is nearly straight; it gives attach- 

 ment to the pharyngeal fascia and the palato-pharyngeus muscle, and bears a cornu 

 at each end. The anterior cornu (Cornu orale) articulates with the cartilage of the 



