298 THE NERVOUS SYSTEM 



proximity to the viscera and from which those viscera are to be 

 directly supplied, as the semilunar, and (c)' terminal ganglia 

 which the fibers reach just before final distribution, as the car- 

 diac, intestinal, etc. The sympathetic is, therefore, frequently 

 known as the ganglionic system. 



Arrangement. There is on each side of the spinal column, 

 extending from the lenticular ganglion above to the ganglion 

 impar below, a chain of ganglia all of which are united to each 

 other and to the ganglia of the opposite chain by commissural 

 fibers. From these ganglia go fibers to form numerous plexuses 

 and to be distributed to the various parts. In the skull there 

 are four of these ganglia, the otic, ophthalmic, submaxillary 

 and spheno-palatine or Meckel's; in the cervical region there are 

 three ; in the dorsal twelve ; in the lumbar four ; in the sacral four 

 or five; and in front of the coccyx the single ganglion impar. 



Connections between the cranial nerves and cranial sympa- 

 thetic ganglia have already been noted. 



The cervical ganglia are of special interest as furnishing the 

 chief sympathetic supply to the heart. 



The thoracic or dorsal ganglia give rise to the sympathetic 

 supply for the great abdominal viscera. From the sixth, seventh, 

 eighth and ninth springs the great splanchnic nerve, which 

 passes through the diaphragm to the semilunar ganglion. This 

 is the largest of the sympathetic ganglion, and is sometimes called 

 the abdominal brain. It has been inaccurately called the center 

 of the sympathetic system. The two ganglia occupy positions 

 on opposite sides of the celiac axis, and give rise to fibers which 

 supply most of the abdominal viscera. The tenth and eleventh 

 thoracic ganglia give rise to the lesser splanchnic nerve. From 

 the last thoracic springs the renal splanchnic nerve. The 

 radiating fibers from the semilunar ganglia form the solar plexuses 

 for the two sides. 



The lumbar ganglia give off fibers to form the aortic lumbar 

 and hypogastric plexuses. 



