The Head and Neck. 247 



exposed; also on the lateral-wall the pharyngeal aperture 

 of the auditory tube (ostium pharyngeum tubae). 

 10. Examination of the larynx. 



By cutting around the base of the tongue on the opposite side 

 of the body, the whole structure, together with the hyoid, larynx, 

 and a portion of the trachea back to about the end of the thyreoid 

 gland may be removed. This affords a good opportunity of re- 

 dissecting on the opposite side from the medial surface of the 

 mandible outward, also of clearing and examining the hyoid appar- 

 atus, which is not usually available with the prepared skeleton 

 (Fig. 65). The laryngeal cartilages should be cleared externally 

 and the parts made out as follows : 



(a) The thyreoid cartilage (cartilago thyreoidea) forms 

 the largest portion of the structure. It is an unpaired saddle- 

 shaped cartilage, described as consisting of right and left 

 laminae. Its anterodorsal angle projects forward as the 

 cornu superior; connected by ligament with the greater 

 comu of the hyoid. The corresponding posterodorsal angle, 

 the cornu inferior, overlies the dorsolateral portion of the 

 cricoid cartilage. The anterior dorsal portion of each plate 

 bears a small thyreoid foramen (foramen thyreoideum) for 

 the entrance of the superior laryngeal nerve. 



(b) The cricoid cartilage (cartilago cricoidea) is an annular 

 cartilage, partly enclosed by the posterior portions of the 

 thyreoid laminae and surrounding the first tracheal ring; 

 Its ventral portion, the arch of the cricoid cartilage, falls 

 some distance behind the thyreoid cartilage, the intervening 

 space being largely occupied by the cricothyreoidei 

 muscles. Its dorsal portion, the lamina of the cricoid, 

 forms a greatly expanded plate serving for the support of the 

 arytenoid cartilages. 



(c) The paired arytenoid cartilages (cartilagines arytenoi- 

 deae) lie one on either side of- the anterior tip of the cricoid 

 plate. 



(d) The corniculate cartilages (cartilagine'? corniculatae) are 

 slender curved terminal cartilages supported by the ary- 

 tenoids. 



