THE SYMPATHETIC NERVE SYSTEM. 215 



THE SYMPATHETIC NERVE SYSTEM. 



The sympathetic nerve system consists of a chain of ganglia 

 connected by longitudinal nerve filaments, situated on each side of 

 the spinal column, running from above downward. The two gangli- 

 onic cords are connected in the interior of the cranium by the ganglion 

 of Ribes, on the anterior communicating artery, and terminate in the 

 ganglion impar, situated at the top of the coccyx. 



The chain of ganglia is divided into groups, and named according 

 to the location in which they are found viz., cranial, four in num- 

 ber ; cervical, three ; thoracic, twelve ; lumbar, five ; sacral, five ; 

 coccygeal, one. Each ganglion consists of a collection of vesicular 

 nervous matter, bundles of non-medullated nerve-fibers, embedded in 

 a capsule of connective tissue. The ganglia are reinforced by motor 

 and sensory fibers from the cerebro-spinal nervous system. 



The ganglia have distinct nerve-fibers, from which branches are 

 distributed to the glands, arteries, and muscles, and to the cerebral 

 and spinal nerves, many pass, also the visceral ganglia e. g., cardiac, 

 semilunar, pelvic, etc. 



Cephalic Ganglia. 



1. The ophthalmic or ciliary ganglion is situated in the orbital 

 cavity, posterior to the eyeball ; it is of small size and of a reddish- 

 gray color ; receives filaments of communication from the motqjpl 

 oculi ophthalmic branch of the fifth pair, and the carotid plexus. 

 Its filaments of distribution are the ciliary nerves, which con- 

 sist of 



(a) Motor fibers for the circular fibers of the iris and ciliary 

 muscle. 



(b) Sensor fibers for the cornea, iris, and associated parts. 



(c) Vaso-motor fibers for the blood-vessels of the choroid, iris, 

 and retina. 



(d} Motor fibers for the dilator fibers of the iris. 



2. The spheno-palatine or Meckel's ganglion, triangular in shape, is 

 situated in the sphenomaxillary fossa ; receives filaments from the 

 facial (Vidian nerve) and the superior maxillary branch of the 

 fifth nerve. Its filaments of distribution pass to the gums, the 

 soft palate and associated parts. 



3. The otic or Arnold's ganglion is of small size, oval in shape, and 

 situated beneath the foramen ovale ; receives a motor filament from 



