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and functions of the nerves. 
going directly out betwixt the vertebras, as the regular spinal 
nerves do, it passes up into the skull, comes out through 
the skull with the par vagum, and, descending upon the neck, 
goes to the muscles of the shoulder. In this course it supplies 
muscles which are already profusely supplied by the regular 
system of nerves. 
This nerve controuls the operations of the muscles of the 
neck and shoulder in their office as respiratory muscles, when, 
by lifting the shoulders, they take the load from the chest, 
and give freedom to the expansion of the thorax. When it is 
cut across in experiments, the muscles of the shoulder, which 
were in action as respiratory muscles, cease their co-opera- 
tion, but remain capable of voluntary actions. 
4. Great internal respiratory nerve. The phrenic, or dia- 
phragmatic, of authors. This is the only nerve of the system 
which has been known as a respiratory nerve. Its origin, 
course, and destination, are so familiar to every one, that I shall 
not say anything more of it here. But there is another nerve, 
which has a remarkable resemblance to it, and which, from 
circumstances already noticed, has been entirely overlooked. 
This is 
5. The external respiratory nerve. This has a similar origin 
with the preceding nerve. It comes out from the cervical 
vertebras, and is connected with the phrenic nerve. It runs 
down the neck, crosses the cervical and axillary nerves, passes 
through the axilla, and arrives on the outside of the ribs, 
where, it is scarcely necessary to observe, the muscles are 
already supplied by nerves coming out betwixt the ribs from 
the system of regular nerves. 
These four last mentioned nerves govern the muscles of 
