THE VOICE AND SPEECH. 643 
geal contains the motor fibers for the crico-thyroid (possibly 
also the arytenoideus posticus) and also supplies the mucous 
membrane. The inferior laryngeal supplies all the other mus- 
cles. While both of these nerves are derived from the vagus, 
their fibers really belong to the spinal accessory. It is worthy 
of note that the entire group of muscles making up the sphinc- 
ter of the larynx is contracted when the inferior laryngeal is 
stimulated. 
Above the true vocal bands lie the so-called false vocal 
bands (cords) which take no essential part in voice-production. 
Between these two pairs of bands are the ventricles of Morgagni, 
which, as well as the adjacent: parts, secrete mucus and allow 
of the movements of both sets of bands and in so far only as- 
sist in phonation. 
What is the nature of the nervous connections by which 
the muscular movements necessary for voice-production is ac- 
complished. They are certainly more complex in nature, at 
least in all their highest manifestations, than might at first 
appear. 
Volition is unquestionably the starting-point, but the result 
is modified by a great variety of afferent impulses, including 
those from the larynx and supra-laryngeal cavities, the thorax, 
lungs, even the ear, and possibly the eye. Muscular co-ordina- 
tions of the most delicate kind must be effected, seeing the fine 
shades in pitch and quality which a first-rate singer can pro- 
duce, 
To watch, with the laryngoscope, these changes in the vocal 
bands alone, gives one an idea of the complexity and perfection 
of such adjustments which no verbal description can convey. 
It is impossible for a deaf man, or one defective in sensibility 
in the regions concerned in phonation, to produce good musical 
tones. No doubt one born blind, and without those stored 
experiences derived from countless pictures, can but very im- 
perfectly make adaptations in singing dependent on such ex- 
perience; and one has only to hear deaf-mutes, who have 
learned to speak from imitation of the speech-movements of 
normal persons, to become convinced of how important a part 
the ear plays in vocalization. The efforts of such persons near- 
ly always seem to be out of harmony with the surroundings. 
There are many subjects connected with the production of 
the singing-voice especially which have been matters of ani- 
mated controversy, chiefly because investigators have restricted 
their observations to an unduly limited range of facts. 
