THE NERVOUS SYSTEM. 335 



THE SYMPATHETIC NERVOUS SYSTEM. 



The sympathetic system, like the cerebro-spinal axis, is 

 double, consisting of a gangliated cord on each side, extending 

 the entire length of the vertebral column, and numerous nerve- 

 fibres, both corrtmunicating , by which it anastomoses with the 

 cerebro-spinal axis, and distributary, by which the blood-vessels 

 and viscera are supplied. 



Branches of the ganglionated cords ascend through the 

 carotid canal to communicate with the ganglia of the fifth cranial 

 nerve, and also with each other through the ganglion of Ribes, 

 situated upon the anterior communicating artery. They also 

 communicate below in the ganglion impar, located in front of 

 the coccyx. 



The ganglia of each cord correspond very nearly in position 

 and number to the vertebra, except in the cervical region, where 

 there are but three: cervical three, dorsal twelve, lumbar four, 

 sacral five. 



From the ganglionated cords three important plexuses are 

 given off the cardiac, solar, and hypogastric situated in the 

 thoracic, abdominal, and pelvic cavities respectively. 



Cranial Ganglia Ganglia Connected with the Fifth Cranial 

 Nerve. Besides the Gasserian ganglion upon the root there are 

 four ophthalmic, spheno-palatine, otic, and submaxillary each 

 of which have three branches of communication or roots motor, 

 sensory, and sympathetic besides several branches of distribu- 

 tion. 



The ophthalmic, or ciliary, ganglion is situated in the orbit 

 between the external rectus muscle and optic nerve upon the first 

 division of the fifth cranial nerve. 



Its sensory root is from the nasal branch of ophthalmic, 

 motor root from the motor oculi or third and sympathetic from 

 the cavernous plexus. 



Its branches are the short ciliary nerves (vide Eye). 



Spheno-palatine, or Meclcel's, the largest, is situated in the 

 spheno-maxillary fossa upon the superior maxillary, or second 

 division of the fifth. 



Its sensory root is derived from the superior maxillary, its 

 motor root, from the facial, through means of the Vidian, and its 

 sympathetic from the carotid plexus. Its branches are : 



1. Ascending; 



,. ( Anterior, or large palatine, 



2. Descending, or 1 Midd] ^ e xteraafpalatii4, 



palatine, | Posterior, or small palatine; 



