

THE THORACOLUMBAR SYMPATHETICS 



975 



in these ganglia, pass through gray rami communicantes to alt the spinal nerves, 

 and are distributed with their cutaneous branches, ultimately leaving these branches 

 to join the small arteries. The post gangl ionic fibers do not necessarily return to 

 the same spinal nerves which contain the corresponding preganglionic fibers. The 

 vasoconstrictor fibers to the head come from the upper thoracic nerves, the pre- 

 ganglionic fibers end in the superior cervical ganglion. The postganglionic fibers 

 pass through the internal carotid nerve and branch from it to join the sensory 

 branches of the various cranial nerves, especially the trigeminal nerve ; other fibers 

 to the deep structures and the salivary glands probably accompany the arteries. 



Auriculotemporal 

 -Parotid gland 



-Tympanic nerve 



FIG. 843. Sympathetic connections of the otic and superior cervical ganglia. 



ie postganglionic vasoconstrictor fibers to the bloodvessels of the abdominal 

 viscera arise in the prevertebral or collateral ganglia in which terminate many 

 preganglionic fibers. Vasoconstrictor fibers to the pelvic viscera arise from the 

 inferior mesenteric ganglia. 



The pilomotor fibers to the hairs and the motor fibers to the sweat glands appar- 

 ently have a distribution similar to that of the vasoconstrictors of the skin. 



A vasoconstrictor center has been located by the physiologists in the neighbor- 

 hood of the facial nucleus. Axons from its cells are supposed to descend in the spinal 

 cord to terminate about cell bodies of the preganglionic fibers located in the dorso- 

 lateral portion of the anterior column of the thoracic and upper lumbar region. 



The motor supply to the dilator pupillse muscle of the eye comes from pregan- 



