THE CERVICAL PLEXUS 355 



The Cervical Nerves 



Of the posterior divisions, that of the first or suboccipital 

 does not divide into an external and internal branch. It crosses 

 the atlas to the suboccipital triangle, and supplies the corn- 

 plexus (in part), the obliqui, and posterior recti, a branch 

 joining the second nerve. Of the other nerves, the external 

 branches supply the splenius, transversalis colli, cervicalis 

 ascendens, and trachelomastoid. The internal, except that of 

 the second, run inward; those of the third, fourth, and fifth, 

 between the complexus and semispinalis, supply them and 

 the multifidus and the skin over the trapezius. The internal 

 branches of the sixth, seventh, and eighth run beneath the 

 semispinalis, and supply no cutaneous branches. The internal 

 branch of the second, known as the great occipital nerve, pierces 

 the trapezius and complexus (in part), supplies the latter, 

 and runs with the occipital artery supplying the back of the 

 head, and sends a branch to the small occipital. 



The Cervical Plexus 



The cervical plexus is formed by the anterior divisions of 

 the upper four cervical nerves, which emerge between the 

 scalenus medius and rectus anticus major. It lies upon the 

 scalenus medius and levator anguli scapulae, beneath the 

 sternomastoid. Each nerve except the first divides into a 

 branch for the nerve above and one for the nerve below. The 

 anterior division of the first (suboccipital) nerve grooves the 

 atlas beneath the vertebral artery, and joins the second, supply- 

 ing the rectus lateralis and recti antici. It communicates 

 with the sympathetic, vagus, and hypoglossal nerves. 



Its branches are superficial and deep. 



The superficial are divided into ascending and descending. 



1. ASCENDING BRANCHES. (a) The superficialis colli, from the 

 second and third nerves, crosses the sternomastoid, and divides 

 under the platysma into two branches, an upper and a lower, 

 .which ramify in the skin of the front of the neck, from the 

 maxilla to the sternum. 



(b) The auricularis magnus, from the second and third, 

 runs over the sternomastoid to the parotid region, and supplies 



