320 PRACTICAL ANATOMY. 



intervertebral foramina and form a mixed nerve, which 

 divides into posterior smaller and anterior larger branches, 

 the latter forming the plexuses from which the nerves are 

 derived that are distributed to the periphery. 



Cervical Nerves. 



The first cervical emerges from the spinal canal above 

 the atlas; the last cervical, between the last cervical 

 and first dorsal vertebra. The anterior branches of the 

 upper four cervical nerves unite to form the cervical 

 plexus, which rests upon the levator anguli scapulae and 

 scalenus anticus muscles. It is formed by communi- 

 cating filaments passing from the first to second, second 

 to third, third to fourth nerves, and sends off two sets 

 of branches, superficial and deep. The superficial 

 branches are divided into the ascending and descending. 

 The ascending branches are : 



1. Superficialis colli, from second and third cervical; 

 winds around the posterior border of sterno-mastoid 

 and is distributed to the side and anterior part of the 

 neck. 



2. Auricularis magnus, from second and third cervi- 

 cal ; winds around posterior border of sterno-mastoid and 

 divides into branches to the face, ear, and occiput. It is 

 the largest superficial branch. 



3. Occipitalis minor, from second cervical; winds 

 around posterior border of sterno-mastoid and is distrib- 

 uted to the occipital region. 



The descending branches are the sternal, clavicular, 

 and acromial, to the regions named. 



The deep branches of the cervical plexus are : 

 1. The phrenic the most important from the third 

 and fourth cervical; runs down the neck, lying on the 

 scalenus anticus, then on the subclavian artery, descends 



