CARTILAGES OF THE LARYXX. 



281 



Fi-. ISS. 



of the pharynx, and affords attachment by means of areolar tissue, to 

 the thyroid body. On their internal surfaces, the two aliB are smooth 

 and slightly concave. Of the four cornua, all of wliich bend inwards. 



Fig. 1S8. — Cartilages of toe 

 Larynx seen from behind and 

 ON THE Right (Bishop). 



h, {, thyroid cartilage ; the right 

 ala is seen foreshortened ; below e, the 

 oblique line on its outer surface ; b, 

 superior, and c, inferior coi'nu of the 

 right side ; cl, ci-icoid cartilage ; to the 

 left of /(, anterior narrow part of the 

 ring ; a, a, arytenoid cartilages ; /, /, 

 epiglottis, the lines point to little 

 pits (for glands) on its surface. 



the two superior or great cornua 

 (fig. 188, h, b), pass slightly 

 backwards, and terminate 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 

 (fig. 180). The inferior or 

 smaller cornua (fig. 188, c), 

 ■which are somewhat thicker 

 but shorter, are directed 

 slightly forwards, and each 

 presents, on the inner aspect 

 of the tip, a smooth surface, 

 for articulation with a prominence on the side of the cricoid cartilage. 

 The cricoid cartilage (fig. 188, el), so named from being shaped 

 like a signet-ring, is thicker and stronger than the thyroid. It is 

 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 diminished to a fourth or a fifth of an inch. 

 Corresponding with this, the superior harder is markedly elevated 

 behind, and descends with a deep concavity in front below the 

 thyroid cartilage ; while the inferior border is horizontal, and connected 

 by membrane to the first ring of the trachea. The posterior elevated 

 part of the upper border is slightly depressed in the middle line (fig. 

 188) ; and on tlie sides of this depression are two convex oval articular 

 facets, directed upwards and outwards, which form a movable joint with 

 the arytenoid cartilages. The exlerjial surface of the cartilage is convex 

 and smooth in front and at the sides, where it affords attachment to the 

 crico-thyroid muscles, and behind these to the inferior constrictors of 

 the pharynx : in the middle line posteriorly is a slight vertical ridge 

 (fig. 189, c) to which some of the longitudinal fibres of the oesophagus 

 are attached. On each side of this ridge is a broad depression occupied 

 by the posterior crico-arytenoid muscle, outside which is a small 

 rounded and slightly raised surface for articulation on either side with 

 the inferior cornu of the thyroid cartilage (fig. 188, c). The infernal 

 surface is covered throughout by the mucous membrane of the larynx. 

 The lower border of the cricoid is circular, but higher up the cartilage 



