150 EQtJINE ANATOMY. 



NEUROLOGY. 



Seventeen pairs of dorsal nerves from the spinal mar- 

 row, all of which are alike, having a superior branch, 

 running towards the spinous process of the dorsal ver- 

 tebrae, ramifying in the spinal muscles and the skin of 

 the dorso-lumbar region; and an inferior branch which 

 runs downwards between the intercostal spaces and end 

 in the intercostal, pectoral and abdominal muscles. The 

 first and second pair cooperate to form the brachial 

 pelxus (see page 63). 



Dorsal portion of the sympathetic. — From the 

 inferior cervical ganglion to the diaphragm it forms 

 a double chain of ganglions, seventeen in number, situ- 

 ated in the costo-vertebral groove, continued posteriorly 

 by the lumbar sympathetic. It has afferent branches 

 coming from the dorso-spinal nerves and efferent 

 branches in small number, among which the small and 

 great splanchnic only are important. The latter leaves 

 the main trunk near the sixth or seventh ganglion, 

 runs backwards, penetrates the abdomen, where it ter- 

 minates in the semi-lunar or solar plexus (see abdomnal 

 cavity, page 174). 



