688 



and glands 

 at the base ; 



glands at 

 the side, 



and beneath 

 tip. 



Nerves 

 from three 

 sources : 



lingual of 

 fifth, 



twelfth, 

 and ninth. 



Arteries, 

 veins, and 

 lymphatics. 



DISSECTION OF THE LARYNX. 



The lingual glands are racemose, similar to those of the lips and 

 cheek, and are placed beneath the mucous membrane on the dorsum 

 of the tongue behind the circumvallate papillae. A few are found 

 in front of the circumvallate papillae, where they project into the 

 muscular substance. Some of their ducts open on the surface and 

 others in the hollows around the circumvallate papillae, or into the 

 foramen caecum and the depressions of the crypts. 



Opposite the circumvallate papillee, at the margin of the tongue, 

 is a small cluster of mucous glands. Under the tip of the tongue, 

 on each side of the fraenum, is another elongated collection of the 

 same kind of glands embedded in the muscular fibres, from which 

 several ducts issue. 



NERVES. There are three nerves on the under surface of each 1 

 half of the tongue, viz., the lingual of the fifth, the hypoglossal, and 

 the glosso-pharyngeal (fig. 224, p. 624). 



The lingual nerve sends upwards filaments through the muscular 

 substance to the mucous membrane of the anterior two-thirds j 

 of the tongue, and supplies the conical and fungiform papillae. 

 Accompanying this nerve are the lingual fibres of the chorda 

 tympani. 



The hypoglossal nerve is spent in long slender offsets to the mus- 

 cular substance of the tongue. 



The glosso-pharyngeal nerve divides under the hyo-glossus into two 

 branches. One turns to the dorsum, and ramifies in the mucous 

 membrane behind the foramen caecum, supplying also the circum- 

 vallate papillae. The other passes to the side of the tongue, and 

 ends in branches for the mucous membrane, extending forwards to 

 about the middle of the border. 



VESSELS. The arteries are derived from the lingual of each side : 

 the veins pass to the internal jugular trunk. The lymphatics of the 

 tongue for the most part pass backwards to the upper deep cervical 

 glands, and have connected with them two or three small lingual 

 glands on the outer surface of the hyo-glossus muscle ; but some 

 descend to the submaxillary lymphatic glands. 



SECTION XV. 



DISSECTION OF THE LARYNX. 



General 

 construc- 

 tion of 

 larynx. 



Dissection. 



The LARYNX is the upper dilated part of the airtube, in which 

 the voice is produced. It is constructed of several cartilages united 

 together by ligamentous bands ; of muscles for the movement of 

 the cartilages ; and of vessels and nerves. The whole is lined by 

 mucous membrane. 



Dissection. The tongue may be removed from the larynx by 

 cutting through its root, but this is to be done without injuring the 

 epiglottis. 



