of the chest in breathing, speaking, and expression, 301 
may be presented under the heads of pathology, and ex- 
pression. 
Of pathology , as illustrated by a knowledge of the respiratory 
system of nerves . 
When we survey the full extent of the respiratory system 
of nerves, we are prepared to comprehend its importance to 
the continuance of life. The infant born without a brain can 
breathe if the origins of these nerves be entire. Deep wounds 
of the brain, though eventually fatal, are not necessarily, or 
instantly so. The man wounded in the spine below the ori- 
gins of the nerves which we have traced, drags on existence 
for a time ; but a bruise on the part of the medulla oblongata, 
from which these nerves take their departure, is death in the 
instant; a breath is not drawn again. 
In describing the effects of violence on the medulla oblon- 
gata, authors have attributed the sudden death to injury of 
the roots of the nerves of the par vagum ; and yet we have a 
statement from the same authority, that an animal will sur- 
vive the division of both nerves of the par vagum. Now that 
we find that many respiratory nerves depart from the same 
centre, and go out to all the parts of the muscular frame, 
which move in respiration, we can better comprehend, how 
injury of the medulla oblongata suppresses at once the act of 
respiration in the nostrils, throat, and windpipe, and the ac- 
tion of the muscles both without and within the chest ; even 
the expression of the agony of dying is, by the injury of the 
roots of all these nerves, suddenly interrupted, and actual 
death follows quickly, owing to the cessation of the respira- 
tory functions. 
