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ANATOMY AND PHYSIOLOGY 



CERVICAL NERVES 



Posterior divisions. These send branches to the back of the 

 head as well as muscles and skin of the neck. Largest posterior 

 branch. The great occipital (from second cervical), to supply the 

 scalp. 



Anterior divisions. The upper four form the cervical plexus. 

 The lower four enter the brachial plexus. 



FIG. 182. THE PHRENIC NERVES, RIGHT AND LEFT, RUN DOWNWARD ON EITHER 

 SIDE OF THE GREAT VESSELS AND THE HEART. (After Morris.) 



The cervical plexus. Most of the branches of this plexus 

 supply muscles of the neck (front and side). One exception is 

 the great auricular (auricularis magnus) which supplies the external 

 ear. Another is the 



Most important nerve of this plexus, the phrenic. It passes 

 downward through the thorax (between the lung and heart) to 

 supply the diaphragm (Fig. 182). Its importance is due to the 

 fact that the diaphragm is one of the principal breathing muscles, 



