THE TONGUE 391 
the ventral surface of the tip. It varies considerably in thickness. On the dorsum 
it is very thick and dense; underneath this part there is a dense fibrous cord, which 
extends medially a distance of five or six inches forward from the vallate papille. 
On the sides and ventral surface of the tongue the membrane is much thinner and 
smooth, and can more readily be dissected off the muscular tissue.!. From the 
lower surface of the free part of the tongue a fold of the mucous membrane passes 
to the floor of the mouth, forming the frenum lingua. Posteriorly a fold passes 
on each side from the edge of the dor- 
sum to join the soft palate, forming the 
anterior pillars of the latter. A thick : 
central glosso-epiglottic fold (Plica gland 
glossoepiglottica) passes from the root 
to the base of the epiglottis; this en- 
closes the hyoepiglottic muscle. The 
Trachea 
Crico-arytenoid- 
Cus dorsalis 
muscle 
Arytenoideus 
muscle 
mucous membrane presents numerous Arytenoid carti- 
papilla, which are of four kinds—fili- lages 
form, fungiform, vallate, and foliate. 
The filiform papille (Papille filiformes) 
are fine, thread-like projections which 
stud the dorsum and the sides of the 
tip; they are absent on the root. On 
the anterior part they are so small.as 
to be scarcely visible, but on the pos- 
terior part they are much larger’ and 
give the surface a distinct pile. .The Folate 
fungiform papille (Papillie fungiformes) papile 
are larger and easily seen; they are  Vallate 
rounded at the free end, which is sup- — PaPll@ 
ported by a neck. They occur princi- 
pally on the lateral part of the tongue, 
but are also found scattered over the 
dorsum. The vallate papille (Papillee 
vallatz) are usually two or three in 
number. The two constant ones are a 
quarter of an inch or more (ca. 6 to 7 
mm.) in diameter, and are found on 
the posterior part of the dorsum, one 
on each side of the median plane, about 
an inch (ca. 3 em.) apart. The third, 
when present, is behind these, is cen- 
trally situated, and is always smaller. 
Rarely a fourth may be found. They 
are rounded, broader at their exposed 
than at their attached surfaces, and are Fic. 331—Toneur, Larynx, AND Part oF TRACHEA OF 
sunk in a depression which is bounded Horse; Dorsat View. 
by an annular wall. Their free surface 
is tuberculate, 7. e., bears small, round secondary papilla. The foliate papilla 
(Papille foliate) are situated just in front of the anterior pillars of the soft palate, 
Where they form a rounded eminence about an inch (ca. 2 to 3 em.) in length, 
marked by transverse fissures. The last three varieties are covered with micro- 
scopic secondary papille and are furnished with taste-buds. The mucous mem- 
brane of the root of the tongue presents numerous folds and rounded elevations. 
Vocal cord 
Aditus laryngis 
E piglottis 
Tonsil 
Radix lingue 
Anterior pillar of 
soft palate (cut) 
Dorsum lingue 
Apex lingue 
_. +The mucous membrane is thick and closely adherent where food naturally comes in contact 
with the tongue. 
