Crista arcuata 



Fovea oblongatt. for 

 thyro-ary noideu 

 muscle 



Muscular process 



lage of Santorini 



Tubercle for false 

 <<! 

 rea triangularis 



Anterior border 

 Vocal process - 



Articular facet 



Articular facet 



I8l6 HUMAN ANATOMY. 



iHiSrf:S|5p?S 



l.; 4 third u d fourth 1-randnal bars. The more membranous part of the ligament 



extends from the superior border and the inner side of the superior horns of the 



1 ; i i to the upper border of the body of the hyoid and its S^er horn A^rsa 



extending under Ihe body of the hyoid, lies on the anterior surface of this membrane, 



WhlC The l1 Arytenoid 1 Cartilages. These are a pair of very irregular four-sided 

 pyramids (one side being the base) perched on the superior articular facets i of the 

 cricoid The vocal cords extend between them and the entering angle of the thyroid. 

 . les the base, there is a posterior, an internal, and an antero-external surface, sep- 

 arated by tolerably distinct borders. A section near the base is semilunar, the bound- 

 ary between the posterior and internal surfaces being effaced. The two remaining 

 angles are each prolonged (Fig. 1542). The anterior, extending forward as j the vocal 



process for the attachment 



FIG. 1542. of the true vocal cord, is 



A long and slender ; the ex- 



ternal or muscular process, 

 short and thick, projects out- 

 ward and backward. The 

 base is chiefly occupied by 

 an oval articular cavity rest- 

 ing on that of the cricoid. 

 The long axis of this articu- 

 lar facet, which does not 

 much surpass its transverse 

 one, extends in the main for- 

 ward, crossing that of the opposed facet. The concavity is nearly at right angles to 

 the long axis. The posterior surface is well defined and deeply concave, being filled 

 by the arytenoid muscle. The internal surface is nearly plane, offering nothing for 

 description. The antero-external surface is triangular. A ridge, the crista arena ta, 

 starts from the vocal process and runs backward and upward, ultimately describing 

 nearly a circle around a hollow, the fovea triangularis, which is quite as often oval. 

 This little hollow is filled by a mass of glands, and is overlooked unless the cartilage 

 be cleaned very can-fully. The false vocal cord is attached to a little tubercle on this 

 rid-, either above or behind the fovea. The borders meet above at a blunt apex. 



The Crico-Arytenoid Joint. From the foregoing description of the two 

 opposed articular surfaces it is evident that in consequence of the crossing of their 

 long axes the whole of one is not in contact with the whole of the other. The joint 

 i, surrounded by a lax cnf>sult\ strengthened behind by straight vertical fibres, which 

 have been called the posterior crico-arytenoid ligament (Fig. 1541). The motions 

 are very diiticult t analyze. The arytenoid may tip on the elongated elevation of 

 the < ricoid or slide alony it ; moreover, it may rotate upon it at any point occupied. 

 This movement, from the nature of the surfaces, is a screw motion rather than a true 

 ..n, but the term is siiltu ientlv accurate. 



The Epiglottis. This is a leaf-shaped plate of elastic cartilage which, inserted 



bv its stalk into the aiijje of the thyroid, rises above the hyoid bone and guards the 



entrance into the larvnv The length is some 3.5 cm. The epiglottis expands trans- 



ely and curls foruard over the root of the tongue. Its posterior surface is 



entirelv lY.-e, but les> than the upper half of the anterior surface is exposed. Beuin- 



nin^ at th. free border, \\hich is bent forward towards the tongue, the posterior 



convex, sliejulv i <.n.a\e. and finally convex again, owing to a prominence, 



called the tnbiT,I,\ uhi.h its root forms in the larynx. The free edge is rounded 



ti.msveiselv and the posterior surface in the main concave across. The stalk, when 



well developed, is triangular on section, titling into the angle of the thyroid. The 



Right aryt*" '* 1 cartilage, capped by cartilafce of Santorini. A, antero- 

 lateral aspect ; B, postero-tnedial aspect. X }. 



