NEUROLOGY. 139 



communicates, either directly or indirectly, with the seventh, eighth, and 

 ninth ; in the cavernous sinus and orbital plexus with the third, fourth, fifth, 

 and sixth ; and even with the olfactory, optic, and auditory, by the fine 

 filaments which accompany the nutrient arteries of those several organs in 

 which these nerves expand and terminate ; it also communicates, as has 

 been already noticed, with the several ganglions in the head. In their 

 course along the spinal column, each nerve regularly communicates with 

 eveiy pair of the spinal nerves, with each of the carvical nerves by one 

 and sometimes by two filaments, and with each of the dorsal, lumbar, and 

 sacral nerves by two, so that these nerves may be said to communicate with 

 every nerve in the cerebro-spinal system. The sympathetic nerves have 

 been considered hy some as independent nervous systems, communicating 

 by numerous branches with every portion of the cerebro-spinal system ; by 

 others they are regarded as nervous cords, formed by the union of branches 

 from all the spinal and from several of the cerebral nerves : the latter is ■ 

 probably the more correct view. 



Although perfect symmetry does not exist between these nerves on the 

 right and left sides, yet the diff'erences are but trifling. The sympathetic 

 nerves send off numerous branches, which are chiefly destined to supply 

 the heart and the coats of the great vessels, and all the pelvic and abdo- 

 minal viscera, except the stomach. These branches arise from the gan- 

 glions on these nerves ; of these there are generally three in the neck ; in 

 the back and loins they correspond with the number of vertebrae in those 

 regions, and in the pelvis there are three on each side, and the coccygeal 

 or impar ganglion below. 



The cervical ganglions are three, the superior, middle, and inferior. 

 Sometimes, however, there are four, and at others only two. 



The superior cervical ganglion is of an oval figure and reddish color, 

 extending from the first to the third cervical vertebra ; its upper end is 

 very small, and about half an inch beneath the carotid foramen in the 

 petrous bone. It sends off several branches, superior, inferior, internal, 

 external, and anterior. The superior branches are two in number ; they 

 ascend in the carotid canal to the cavernous sinus, and communicate with 

 the sixth and the vidian branch of the fifth. In the carotid canal they form 

 the internal carotid plexus^ from which some filaments pass through the 

 petrous bone into the tympanum. In this sinus, the ascending small fila- 

 ments again form a plexus named cavernous plexus. From this plexus, 

 filaments pass to the Casserian ganglion, others to the orbital plexus and 

 lenticular ganglion, and the remainder accompany the artery to the brain. 

 The inferior or descending branch is the continued cord of the sympathetic 

 itself which joins the middle or cervical ganglion. The anterior branches 

 are numerous ; some communicate with the eighth and ninth in the great 

 basilar plexus, others surround the external carotid, and divide into fasci- 

 culi which accompany all its branches and form loops and plexuses around 

 each, named from their destination, thyroid, lingual, &c. The external 

 branches join the superior cervical nerve ; they are large and ganglionic. 

 Some join the nervous loop, the principal unite with the second cervical 



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