CERVICAL PLEXUS 



975 



the second loop of the plexus (figs. 751, 752). This branch gives off the small 

 occipital nerve and a filament to the sterno-mastoid, which communicates with 

 the spinal accessory nerve in the substance of the muscle, and it gives branches 

 which assist in forming the hypoglossal or cervical loop (ansa hypoglossi) the cer- 

 vical cutaneous and the great auricular nerves (fig. 752). 



Fig. 751. — Origin of the Cervical and Brachial Plexus. (After Toldt, "Atlas of Human 

 Anatomy," Rebman, London and New York.) 

 Muscular branch to rectus capitis anterior an'i 



Ifltpralis and Innpiis canitis ^^ \ 



lateralis and longus capitis 

 Rectus capitis lateralis 



Internal carotid artery 

 j Rectus capitis anterior 



Muscular branch to longus capitis and longus colli . - ; \ r- 



Communicating branch to descendens ^ i ^j i^iX 1 



cervicalis (hypoglossi) - 4=. — -.'^ I /^y^ 



Small occipital -^ \ / ','//^')f^ ( 



Communicating branch to spinal accessory -.s \ k J/^ <^/^^^^^' 



Great auricular -._ v>,___^II^^5^L--''""S/ yvfl^ i ' 

 Cervical cutaneous ^^-^^"^^^ i}^^' J f/-Sr i 



Muscular branch >.;^ ^k- / / ^^y^ /Ifr 

 Supra-claviculans-i.- — -zi^yi^y/ /C-^^ il 



Phrenic -^ I !j| 1 



Dorsal scapular -y^^/ "\^^xL ' 



Supra-scapular -:;^'^>^ ' ' "-""^ \K'^3k\ 



Medial ulnar .P^:^^^^/^ /// /|/'] 

 Anti-brachial p/^ y/ J 'I /?& 'i 



cutaneous ^-^/^^^''J^ >||||| 



Subscapular <*''-'"'' ^,^-' ' jf»^ 



Long thoracic '" •■ \ 



""^^Sll^ 



Serratus anterior 



Anterior thoracic 



p_. >^' 



Scalenus medius 



Internal car- 

 otid nerve 

 First cervical 



nerve 

 Ramus communi- 

 cans 



Second cervical 

 nerve 



Superior cervical 

 ganglion 



Third and fourth 



cervical nerves 

 Ramus communi- 

 cans 



Vertebral artery 



Gangliated trunk 



' Fifth, sixth and 

 seventh cer- 

 vical nerves 



- Middle cervical 

 ganglion 



Eighth cervical 



nerve 

 Inferior cervical 



ganglion 



First thoracic 

 ganglion 



First thoracic 



nerve 

 Vertebral 



exus 



Subclavian 

 plexus 



Ansa subclavia 

 ^Vieussenii) 



Subclavian 

 artery 



The third and fourth cervical nerves pass behind the vertebral artery (fig. 751) 

 and between the intertransverse muscles to the interval between the scalenus 

 medius and the longus capitis (rectus capitis anterior major), where the third 

 unites with the second and fourth nerves and completes the lower two loops of the 

 plexus. The anterior primary divisions of these nerves are about double the size 

 of the preceding. The third gives off branches to the hypoglossal loop, to the 



