408 Dll, C. F. SONNTAG ON THE ANATOMY, 



C 7 gives off the external anterior thoracic nerve (E.A.T) and 

 forms a trunk which divides into anterior and posterior divisions 

 as in Man. 



C 8 and D 1 unite to form a short trunk which divides into 

 anterior and posterior divisions. At the point of division the 

 internal anterior thoracic nerve (I.A.T) is given off. The two 

 anterior thoracic nerves are connected by a loop as in Man. 



C 5 and the anterior divisions of C 6 and C 7 unite to form a 

 thick cord which, after giving olF the onusculo-cutaneous nerve 

 (M-C.N), unites with the anterior division of the combined C 8 and 

 i)l to form a cord, which divides into median (M.N) and ulnar 

 (U.N) nerves. There is no separation into outer and inner cords 

 as in Man, but the musculo-cutaneous nerve represents the 

 former. 



Text-figure 48. 



CM 

 M-SN' 



\AX EAT. 

 D-E.M. 



The bracliial plexus. C 5-D 1 : lower cervical and first dorsal nerves. 



Letters in te.xt. 



The posterior divisions of C 6, C 7, and the combined C 8 and 

 D 1 unite to form a posterior cord, which gives off four suhscap- 

 ular nerves (U.S.N. , L.S., Lo.S) and divides into the musculo- 

 spiral (M-S.N) and circumflex (C.N) nerves. 



The internal cutaneous (I.C.N), lesser internal cutaneous 

 (L.I.C), and a coraco-hrachial (0-B.N) twigs come from the 

 representatives of the outer and inner cords. 



The suprascapular nerve from C 5, passes through the supra- 

 scapular notch, supplies supra- spinatus and turns through the 

 great scapular notch to supply infra-spinatus. As it passes 

 through the greater notch it gives a second branch to the supra- 

 spinatus. 



