io8 



PRACTICAL ANATOMY. 



superior border of the thyroid cartilage, in the mid-line, you will see the thyroid 

 median notch. Each thyroid ala has a superior cornu and an inferior cornu. 

 The inferior cornu articulates with the cricoid cartilage, forming the crico-thyroid 

 articulation. (Fig. 67.) The superior cornu gives attachment to the lateral 

 thyro-hyoid ligament. The outer surface of the ala has an oblique line, limited 

 above and below by a superior and inferior tubercle respectively. (Fig. 67.) 



The retiring angle of the thyroid cartilage (Fig. 69) gives origin to: (i) 

 The epiglottis ; (2) the false vocal cords ; (3) the true vocal cords ; (4) the 

 thyro-arytenoid muscle ; (5) the thyro-epiglottideus muscle. 



The cricoid cartilage (Figs. 68 and 70) forms, as you will see, a complete 

 ring. It is very narrow in front ; quite wide behind. The arytenoid cartilages 



GREATER CORNU OF 



HYOID BONE 

 CARTILAOO TRITICEA 



SUPERIOR CORNU OF 

 THYROID CARTILAGE 



BRANCH TO LATERAL 

 CRICO ARYTENOID 

 AND TBYRO-ARYTE- 

 .VOID MUSCLES 

 BKANCB JOINING THE 

 SUPERIOR LARYN- 

 GEALKERVR 

 Crico-arytenoldeu* 

 posticus muscle 

 INFERIOR CORNU OF 

 THYROID CARTILAGE 



FORAMEN C/EOUM 

 BASE OF TONGUE 



EXTERNAL LARYN- 

 GJKAL NERVE 



INTERN A L LA R YN- 

 <;I:AL NERVE 



Cut edge of thyro- 

 hyoid membrane 



AryteuoideuB muacle 



RECURRENT 

 LARYNOEAL 

 NER VJ 



FIG. 71. NERVES OF THE LARYNX. (Posterior view.) 



rest upon the superior border of the cricoid, behind, forming a movable articula- 

 tion, called the crico-arylenoid. 



The arytenoids are small. You must learn the following geometrical de- 

 scription of the arytenoids before you can dissect the larynx understandingly, 

 much less understand the action of the arytenoids : 

 Apex, obtruncate and points backward and inward. 

 Base, articulates with the cricoid cartilage. (Fig. 68.) 

 Posterior surface is occupied by the arytenoicleus muscle. (Fig. 68.) 

 Anterior surface for attachment of false cords and thyro-arytenoideus. (Fig. 



/o.) 



Internal surface is covered by mucous membrane. 



Anterior angle, processus vocalis for insertion of true vocal cord. (Fig. 68.) 



