[Illustration: =CONVOLUTIONS AND FISSURES OF THE OUTER SURFACE OF THE CEREBRAL HEMISPHERE.=]
=_RELATION OF THE PROPER USE OF THE VOICE TO THE NERVOUS SYSTEM._=
The vocal organs may be said to be tools, and the nerves the workmen appointed to use them.
Nerves are whitish and elastic bundles of fibers, with their accompanying tissues. They transmit nervous impulses between nerve centers and various parts of the animal body.
“Nerves are composed of one or more (sometimes nearly a hundred) nerve fibers, each fiber forming a means of communication between two parts more or less distant from each other.”—_Dutton._
The brain is contained in the cranium, and may be said to be the controller of the entire nervous system. From it proceed twelve pairs of cranial nerves.
I. Olfactory, nerve of smell,—distributed in the mucous membrane of the nose.
II. Optic, nerve of sight,—distributes its branches to the eye ball.
IV. Patheticus,—assists in moving the eye.
V. Trigeminus,—nerve of sensation, motion, and taste.
VI. Abducens,—assists the movements of the eye.
VII. Facial (or nerve of expression),—moves the face, ear, palate, and tongue. By means of this nerve the tongue is directly connected with the brain, and receives its impulse of action therefrom.
IX. Glosso-pharyngeal, nerve of sensation and taste,—it is distributed to the back of the tongue, middle ear, tonsils, and pharynx.
X. Pneumogastric,—the auriculo-laryngo-pharyngo-œsophago-tracheo-pulmono-cardio-gastro-hepatic nerve. It is a nerve of sensation and motion, probably receiving its motor influence from its spinal accessory.
XI. Spinal accessory furnishes motor power to the pneumogastric.
XII. Hypo-glossal,—motor of the tongue. It communicates with the pneumogastric and sympathetic nerves.
[Illustration: =DIAGRAM OF THE FIRST SIX CRANIAL NERVES, WITH THEIR CHIEF BRANCHES OF DISTRIBUTION.=]
[Illustration: =DIAGRAM OF THE LAST SIX CRANIAL NERVES, WITH THEIR CHIEF BRANCHES OF DISTRIBUTION.=]
My principal object in writing of the relation of the voice to the nervous system is to show anatomical and physiological reasons for denominating the voice the reporter of the states of mind.
We have before us the names of the nerves which connect the organs of speech with the organ of thought. Through some of the cranial nerves the mind immediately discharges its impulses upon certain organs, both consciously and subconsciously. This is illustrated by the motor occuli, patheticus, and abducens, which move the eye sometimes consciously and sometimes subconsciously. This shows that these nerves may, and often do, act upon the eye, without any conscious plan or purpose on the part of the individual.
