Sneezing and coughing, however, can be controlled by the will only
partially or not at all; whilst the clearing the throat and blowing
the nose are completely under our command.
[10] "Dr. Maudsley, `Body and Mind,' 1870, p. 8.
When we are conscious of the presence of an irritating particle
in our nostrils or windpipe--that is, when the same sensory
nerve-cells are excited, as in the case of sneezing and coughing--
we can voluntarily expel the particle by forcibly driving air
through these passages; but we cannot do this with nearly
the same force, rapidity, and precision, as by a reflex action.
In this latter case the sensory nerve-cells apparently excite
the motor nerve-cells without any waste of power by first
communicating with the cerebral hemispheres--the seat of our
consciousness and volition. In all cases there seems to exist
a profound antagonism between the same movements, as directed
by the will and by a reflex stimulant, in the force with which they
are performed and in the facility with which they are excited.
As Claude Bernard asserts, "L'influence du cerveau tend donc
a entraver les mouvements reflexes, a limiter leur force
et leur etendue.
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