DISSECTION OF THE HEAD AND NECK 313 



Observe that this ligament is simply the thickened 

 lower margin of the quadrangular membrane. 



Next dissect away on the right side the remains of the plica 

 aryepiglottica, membrana quadrangularis, plica ventricularis, 

 plica vocalis, and comis elasticus, but leave the arytaenoid and 

 corniculate cartilages undisturbed. Remove the cuneiform car- 

 tilage from the right aryepiglottic fold and preserve it for subse- 

 quent study. The left wall of the cavity of the larynx may now 

 be thoroughly studied, and any points not well made out in the 

 preliminary study of the cavity before it was opened should be 

 cleared up before going further. 



Vessels and Nerves of Larynx. 



The dissection of the vessels and nerves of the interior of the 

 larynx should now be undertaken. 



(a) Internal ramus of superior laryngeal nerve (ramus internus 'N. laryn- 



gei superioris). 



(aa) Ramus anastomosing with inferior laryngeal nerve (ramus 

 anastomoticus cum N. laryngeo inferiore) (0. T. Galen's 

 loop). 



Make traction on this nerve outside the larynx where 

 it pierces the membrana hyothyreoidea and cut through the 

 tunica mucosa laryngis on the inner surface of this mem- 

 brane and find the nerve and artery. Gradually dissect off 

 the tunica mucosa and expose their branches. What is the 

 function of the internal ramus of the N. laryngeus superior ? 



(b) Inferior laryngeal nerve from the recurrent nerve (N. laryngeus in- 



ferior N. recurrentis) (0. T. recurrent laryngeal nerve). 



To see it well, draw the thyreoid cartilage well lateral- 

 ward. 



(ba) Anterior ramus (ramus anterior). 



What muscles are innervated by it ? 



(bb) Posterior ramus (ramus posterior). 



What muscles does it supply? 



(c) Superior laryngeal artery (A. laryngea superior). 



(d) Inferior laryngeal artery (A. laryngea inferior). 



Cartilages and Ligaments of Larynx. 



Some of these have already been examined. 



Remove the rest of the mucous membrane and the muscles 

 from the cartilages, taking care not to injure the ligaments or 

 the smaller cartilages. Study 



Epiglottis and its Ligaments, 

 (a) Epiglottis. 



Stem of epiglottis (petiolus epiglottidis) . 



