642 ANIMAL PHYSIOLOGY. 
general anatomy of 
the ‘larynx, we call 
attention briefly to 
the following: 
Widening of the 
glottis is effected by 
the crico - arytenoi- 
deus posticus pull- 
ing outward the pro- 
cessus vocalis or at- 
tachment posterior- 
ly of the vocal band, 
In this and the two following figures the 
@ and a similar effect 
% g is produced by the 
3 arytenoideus posti- 
€ 8 cus acting alone. 
33 g Narrowing of the 
25 glottis is accom- 
plished by the erico- 
arytenoideus  later- 
alis, and the follow- 
ing when acting 
either singly (except 
the arytenoideus 
posticus), or in con- 
cert, as the sphinc- 
ter of the larynx, 
viz., the thyro-aryt- 
enoideus eaternus, 
thyro - arytenoideus 
internus, thyro-ary- 
epiglotticus, aryte- 
noideus posticus. 
Tension of the vo- 
cal bands is brought 
about by the sphinc- 
ter group, and espe- 
cially by the exter- 
nal and internal thy- 
ro - arytenoid mus- 
cles. 
Nerve Supply.— 
The superior laryn- 
proprius 1 
i) 
of posterior crico-arytenoid 
the action of the muscles conce! 
nx to illustrate action of ary 
ion of the parts owing to 
Fie. 481.—Illustrates action of thyro-arytenoideus internus. 
grammatic section of larynx to illustrate action 
y: 
dotted lines indicate the new positi 
Fre. 480.—Dia, 
grammatic section of lar. 
Fie. 479.—Dia, 
