THE NECK, ANTERIOR. 89 



the descendens hypoglossi, which supplies the thyrohyoid 

 muscle, and a recurrent twig to the styloglossus. 



Under the mylohyoid the hypoglossal gives branches to 

 the hyoglossus, geniohyoid, geniohyoglossus, genioglossus, 

 and the muscular substance of the tongue. 



The Cervical Plexus. Figs. 16, 17, 18. 



The cervical plexus is formed by the anterior branches 

 of the four upper cervical nerves, which appear along the 

 side of the neck between the prevertebral and lateral sets 

 of muscles, and are connected in series by interlacing 

 branches. 



A diagrammatic representation of the plexus is given on 

 page 75. Diag. 6. 



Branches. From the loop joining the first and second 

 nerves is given off: 



(1) A branch which passes forward to join the hypo- 

 glossal nerve. 



(2) From the second nerve is given off the small occip- 

 ital. 



(3) From the second and third nerves are given off 

 branches to form the great auricular (4) the superficial 

 cervical and (5) the communicantes hypoglossi. The 

 second and third are joined by a loop. 



From the third proceeds the (6) nerve to the trape- 

 zius. 



From the third and fourth the (7) sternal, (8) clavi- 

 cular, (9) and acromial branches. 



From the fourth (and fifth, of brachial plexus) arises (10) 

 the phrenic. 



(i i) Muscular branches are derived from the first for the 

 rectus capitis lateralis and the rectus capitis anticus minor ; 

 from the first and second, for the rectus capitis anticus 



