of the chest in breathing , speaking , and expression. 305 
affected ; whether directly or indirectly, it is not our present 
business to enquire. He stands stooping forward, resting 
his arms so as to throw the muscles of the chest into opera- 
tion upon the ribs. The position of the head and the rigidity 
of the muscles of the neck, the action of the mastoid muscle, 
and of the cutaneous muscle, visible in the retraction of the 
cheeks and mouth, and the inflation of the nostrils, carry us 
back in review of the nerves and muscles of respiration. 
It will now perhaps be acknowledged, that the methods of 
physiologists, in accounting for the combination of parts in 
the actions of respiration, were very imperfect, or rather 
altogether erroneous. To account for the convulsion of the 
diaphragm in sneezing, they were constrained to go a far 
way about : first, connecting the roots of the phrenic with the 
sympathetic nerve : bestowing sensibility on the latter, which 
it. does not possess : then, following a remote connection be- 
tween it and the nerves of the nose ; then again, counting the 
relations between the facial nerve and the 3rd of the neck : 
they satisfied themselves that they had explained the manner 
in which the diaphragm became convulsed upon irritating the 
membrane of the nose. Another misconception was engrafted 
on the first ; they spoke of these actions as convulsive and 
irregular, which are amongst the most admirable provisions 
for the protection of life. As to the act of sneezing, like 
coughing, it is a consequence of an irritation of the extremity 
of one of the respiratory nerves, whence the whole muscles 
of respiration are brought into action. That there is nothing 
accidental, nor of the nature of convulsion, is shown, by the 
admirable adjustment of the muscles to the object. A body 
irritating the glottis, will call into simultaneous action the 
mdcccxxii. R r 
