Spinal Nerves. 



155 



Of the twelve dorsal 



thoracici, the first passes out 

 of the inter vertebra I fora- 

 men between the first and 

 second dorsal vertebrae, 

 the twelfth between the 

 last dorsal and first lum- 

 bar. Immediately after their 

 exit they divide into lar- 

 ger, anterior, and smaller, 

 posterior divisions. The 

 posterior divisions di- 

 vide into internal and exter- 

 nal branches; both supply 

 the muscles and skin of the 

 back. The anterior di- 

 visions, the intercostal 

 nerves, Nero I inter costales, 

 pass forwards in the inter- 

 costal spaces, each giving off 

 a lateral cutaneous 

 branch, N. cutaneus pecto- 

 ralis lateralis. The upper six 

 lateral cutaneous branches 

 divide again into anterior 

 and posterior, Nervi cu- 

 tand laterales pectoris ante- 

 rior es et posterior es, the for- 

 mer to the integument of the 

 chest and mamma, the latter 

 to the integument of the back. 

 After havinggiven off the 

 lateral cutaneous branches, 

 the intercostal nerves con- 

 tinue their course forwards, 

 supply the intercostal muscles, 

 pierce the M. pectdralis major 

 near the sternum, and are 

 lost as anterior cuta- 

 neous nerves of the chest, 

 Nervi cutanei pectoris anterio- 

 res, in the integument of the 

 mamma and front of the chest. 

 The anterior bran- 

 ches of the six lower lateral 

 cutaneous nerves pass to the 



anterior abdominal wall, the posterior to the 

 cutanei laterales abdominis anteriores et posteriores. 



Heitzmann, Atlas. II. 



R. PROFUND. 

 N. RADIAL. 



N. INTEROSS. EXT. 



R. DORSAL. 

 N. RADIAL. 



R. DORSAL. 

 ~N. ULNAR. 



499. The Nerves at the Extensor 

 Surface of the Upper Extremity. 



skin of the back as Nervi 



21 



