148 HUMAN PHYSIOLOGY. 



The ganglia are reinforced by motor and sensory fibres from the cerebro- 

 spinal nervous system. 



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

 tributed to the 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 distribution are the 

 ciliary nerves, which consist of 



1. Motor fibres for the circular fibres of the iris and ciliary muscle. 



2. Sensory fibres for the cornea, iris and associated parts. 



3. Vasomotor fibres for the blood vessels of the choroid, iris and 

 retina. 



4. Motor fibres for the dilator fibres of the iris. 



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 filaments from the chorda tympani, sensory filaments from the lin- 

 gual branch of the 5th nerve, and filaments from the sympathetic. The 

 chorda tympani nerve supplies vaso-dilator and secretory fibres to the sub- 

 maxillary and sub-lingual glands. The fifth nerve endows the glands with 

 sensibility, while the sympathetic supplies secretory or trophic fibres. 



Cervical Ganglia. 



The Superior cervical ganglion is fusiform in shape, of a grayish-red 

 color, and situate opposite the 2d and 3d cervical vertebrae; it sends 

 branches to form the carotid and cavernous plexuses which follow the 

 course of the carotid arteries to their distribution ; also sends branches to 



