638 NERVOUS SYSTEM. 



been described in connection with these nerves. Its filaments of distribution 

 are the ten or twelve short ciliary nerves, which pass to the ciliary muscle and 

 the iris. A very delicate filament from this ganglion passes to the eye, with 

 the central artery of the retina, in the canal in the centre of the optic nerve. 



The uses of the ophthalmic ganglion are related mainly to the action of 

 the ciliary muscle and iris ; and it is only necessary here to indicate its ana- 

 tomical relations, leaving its physiology to be taken up in connection with 

 the physiology of the sense of sight. 



The spheno-palatine, or Meckel's ganglion, is the largest of the cranial 

 ganglia. It is triangular in shape, reddish in color, and is situated in the 

 spheno-maxillary fossa, near the spheno-palatine foramen. It receives a mo- 

 tor root from the facial, by the Vidian nerve. Its sensory roots are the two 

 spheno-palatine branches from the superior maxillary division of the fifth. 

 It has a large number of branches of distribution. Two or three delicate 

 filaments enter the orbit and go to its periosteum. Its other branches, which 

 it is unnecessary to describe fully in detail, are distributed to the gums, the 

 membrane covering the hard palate, the soft palate, the uvula, the roof of the 

 mouth, the tonsils, the mucous membrane of the nose, the middle auditory 

 meatus, a portion of the pharyngeal mucous membrane, and the levator palati 

 and azygos uvulae muscles. It is probable that the filaments sent to these 

 two striated muscles are derived from the facial nerve and do not properly 

 belong to the sympathetic system. The ganglion also sends a short branch, 

 of a reddish-gray color, to the carotid plexus. 



The otic ganglion, sometimes called Arnold's ganglion, is a small, oval, 

 reddish-gray mass, situated just below the foramen ovale. It receives a mo- 

 tor filament from the facial and sensory filaments from branches of the fifth 

 and the glosso-pharyngeal. Its filaments of distribution go to the mucous 

 membrane of the tympanic cavity and Eustachian tube and to the tensor tym- 

 pani and tensor palati muscles. Reasoning from the general mode of distribu- 

 tion of the sympathetic filaments, those going to the striated muscles are de- 

 rived from the facial. It also sends branches to the carotid plexus. 



The submaxillary ganglion, situated on the submaxillary gland, is small, 

 rounded, and reddish-gray in color. It receives motor filaments from the 

 chorda tympani and sensory filaments from the lingual branch of the fifth. 

 Its filaments of distribution go to Wharton's duct, to the mucous membrane 

 of the mouth and to the submaxillary gland. 



Cervical Ganglia. The three cervical ganglia are situated opposite the 

 third, fifth and seventh cervical vertebrae respectively. The middle ganglion 

 is sometimes wanting, and the inferior ganglion is occasionally fused with 

 the first thoracic ganglion. These ganglia are connected together by the so- 

 called sympathetic cord. They have a number of filaments of communica- 

 tion above, with the cranial and the cervical nerves of the cerebro-spinal sys- 

 tem. Branches from the superior ganglion go to the internal carotid, to 

 form the carotid and the cavernous plexus, following the vessels as they 

 branch to their distribution. Branches from this ganglion pass to the cra- 

 nial ganglia. There are also branches which unite with filaments from the 



