18 



PHYSIOLOGY. 



thoracic to the third lumbar nerves, in fhe cat, and are distributed 

 to the unstriped muscle about the roots of the hairs and cause erec- 

 tion of them. The condition of the skin known as "goose-skin" is 

 due to these nerves. 



Sympathetic fibers, according to their distribution, can be 

 divided into cutaneous or somatic, and visceral or splanchnic. 



/) rter/o/e of H&cwt 



and. 

 "//<w/e fiber 



firlenole 



Fig. 293. Efferent Sympathetic Fiber. 



Afferent fibers take their origin in the ganglion of the posterior 

 root. The efferent fibers arise from the intermedio-lateral column 

 of cells, and pass out by the anterior roots. 



The efferent fibers of the head and neck come from the upper 

 five dorsal nerves, and run up in the cervical sympathetic to the 

 superior cervical ganglion, where they have their cell station. From 

 this ganglion the following fibers arise: 



1. Vasocontrictors. 



