ANTERIOR ASPECT OF HEAD AND NECK. 



upper border and open on a series of papillae found along the 

 summit of the plica sublingualis, a ridge produced in the mu- 

 cous membrane by the upper border of the gland. [1012] 



THE LARYNX. 



This lies in the midline, in front of the pharynx and opposite 

 the fourth, fifth, and sixth cervical vertebrae. 



Cartilages. There are three single ones and three pairs as 

 follows : 



The thyroid cartilage is single and formed by two diverging, 

 quadrilateral plates. The anterior borders are separate above 

 (thyroid notch) but fused below in an angle whose upper part, 

 in males, projects (pomum Adami). The posterior border of 

 each plate is prolonged, above and below, in cylindrical proc- 

 esses (cornua); the superior cornu, the longer and thinner, 

 bends slightly inward and backward ; the inferior cornu curves 

 slightly inward and has, on the inner side of its end, a facet for 

 the cricoid. The superior border is slightly convex, joins the 

 thyroid notch in front, and ends behind in a slight notch. A 

 projection (inferior tubercle) divides the inferior border into a 

 short and concave posterior part, and a longer and concave 

 anterior part. The inner surface is smooth. On the external 

 surface a ridge (oblique line) runs from the inferior tubercle 

 to a prominence (superior tubercle) just below the superior 

 border, in front of the root of the superior cornu. [957] 



The cricoid cartilage is a single ring formed behind by a 

 thick plate (posterior lamina) and completed elsewhere by a 

 curved band (anterior arch) which is thinnest in front; the 

 aperture is circular below but elliptical above. The inner 

 surface is smooth ; the inferior border is nearly horizontal but 

 may have a projection in front and at each side. The posterior 

 lamina presents on its upper border a mesial notch between 

 two facets, for the arytenoids, and on its posterior surface a 

 median ridge between two depressed areas; at its junction 

 with the arch a vertical ridge descends from the arytenoid 



[89] 



