906 



THE LABYNX. 



the larynx, whilst the epiglottis is situated in front, and the cuneiform 

 cartilages on each side of the upper opening. 



The thyroid cartilage is the largest of the pieces composing the frame- 

 work of the larynx. It is formed by two flat lamellae, united in front at an 

 acute angle along the middle line, where they form a projection at the upper 

 part. This angular projection is subcutaneous, and is much more prominent 

 in the male than iii the female, being named in the former the pomum 

 Adami. The two symmetrical halves or lamellae, named the alee, are some- 

 what quadrilateral in form : the anterior border where they are joined is the 

 shortest, the pomum Adami being surmounted by a deep notch ; the 

 posterior free border of each, thickened and vertical, is prolonged upwards 

 and downwards into two processes or cornua, and gives attachment to the 

 stylo-pharyngeus and palato-pharyrigeus muscles ; the superior and inferior 

 borders are both of them concave immediately in front of the cornua, while 

 the superior is convex in its anterior half, and the inferior is nearly straight. 



The external flattened surface of each ala is marked by an indistinct oblique 

 line or ridge, which, commencing at a tubercle situated at the back part of 

 the upper border of the cartilage, passes downwards and forwards, so as to 

 mark off the anterior three fourths of the surface from the remaining pos- 

 terior portion. This line gives attachment below to the sterno- thyroid , and 

 above to the thyro-hyoid muscle, whilst the small smooth surface behind it 

 gives origin to part of the inferior constrictor of the pharynx, and affords 

 attachment, by means of areolar tissue, to the thyroid body. On their 

 internal surfaces, the two alee are smooth and slightly concave, and by their 



Fig. 634. 



Fig. 634. CARTILAGES OF THE LARYNX SEEN FROM 



BEFORE. I 



1 to 4, thyroid cartilage ; 1, vertical ridge or 

 pomum Adami ; 2, right ala ; 3, superior, and 4, 

 infei ior cornu of the right side ; 5, 6, cricoid carti- 

 lage ; 5, inside of the posterior part ; 6, anterior 

 narrow part of the ring ; 7, arytenoid cartilages. 



union in front, form a narrow angle within. 

 Of the four cornua, all of which bend in- 

 wards, the two superior or great cornua, pass 

 backwards, upwards, and inwards, and ter- 

 minate each by a blunt extremity, which is 

 connected, by means of the lateral thyro- 

 hyoid ligament, to the tip of the corresponding 

 great cornu of the os hyoides. The inferior or 

 smaller cornua, which are somewhat thicker 

 but shorter, are directed forwards and inwards, 

 and present each, on the inner aspect of the 

 tip, a smooth surface, for articulation with a 

 prominence on the side of the cricoid carti- 



The cricoid cartilage, so named from being shaped like a ring, is thicker 

 in substance and stronger than the thyroid cartilage. It 13 deep behind, 

 where the thyroid cartilage is deficient, measuring in the male about an 

 inch from above downwards ; but in front its vertical measurement is dimi- 

 nished to a fourth or a fifth of an inch. This diminution is caused by the 

 direction of the superior border, which rises in a convex elevation behind, and 



