312 Mr. Bell on the nerves which associate the muscles, &c. 
down the side of the neck, branching exclusively 
to the trapezius muscle. 
4. The phrenic or diaphragmatic nerve. It is seen 
coming out from the spine, and running a direct 
course to the diaphragm. 
5. The external respiratory nerve of the chest. It is 
like the last nerve in its origin, but it deviates in its 
course, passes on the outside of the chest to supply 
the powerful respiratory muscle, the serratus mag- 
nus E. E. 
These three nerves combine the mastoid and the trapezius 
muscles, the serratus magnus and the diaphragm, with the 
larynx, the tongue, and nostrils. 
6. 7. The nerve of the par vagum. Coming from the 
same origin with the other respiratory nerves, it 
passes down to the internal organs ; but in its 
passage gives off these : 
8. The superior laryngeal nerve, a branch of the last 
nerve. 
9. The recurrent nerve ; a branch also of the nerve 
of the par vagum. Where the nerve of the par 
vagum is in the thorax ( 7 ) at the same time that 
it sends off the recurrent (9), it sends off many 
small nerves to the heart and the lungs, and then 
descends in a plexus on the oesophagus, to the 
stomach. 
