130 HUMAN PHYSIOLOGY. 



SYMPATHETIC NERVOUS SYSTEM. 



The Sympathetic Nervous System consists of a chain of ganglia 

 connected together by longitudinal nerve filaments, situated on each side 

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

 onic cords are connected together 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 tip 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 number; cervical, 

 three ; thoracic, twelve ; lumbar, five ; sacral, five ; coccygeal, one. Each 

 ganglion consists of a collection of vesicular nervous matter, among which 

 are found tubular and gelatinous nerve fibres. The ganglia are reinforced 

 by motor and sensory fibres from the cerebro- spinal nervous system. 



The Ganglia are distinct nerve fibres, from which branches are dis- 

 tributed to glands, arteries, muscles, and to the cerebral and spinal nerves ; 

 many pass, also, to 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 motor oculi, ophthalmic 

 branch of the 5th pair, and the carotid plexus. Its filaments of distribu- 

 tion are the ciliary nerves which pass to the iris and ciliary muscle. 



Function. It is the centre through which the reflex acts take place by 

 which the pupil is contracted or dilated; controls the movement of 

 accommodation for vision at different distances. 



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

 situated in the spheno-maxillary fossa ; receives filaments from the facial 

 (Vidian nerve), and the superior maxillary branch of the 5th nerve. Its 

 filaments of distribution pass to the gums, the soft palate, levator palati 

 and azygos uvulae muscles. 



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 the 

 facial and sensory filaments from the glosso-pharyngeal and 5th nerve ; 

 sends filaments to the mucous membrane of the tympanic cavity and to the 

 tensor tympani muscle. 



4. The Submaxillary ganglion, situated in the submaxillary gland, 

 receives motor filaments from the chorda tympani, and sensory filaments 

 from the lingual branch of the 5th nerve. Regulates to some extent the 

 secretion of saliva. 



