SYMPATHETIC GANGLIA 607 



three cervical ganglia the superior, middle, and inferior. In the chest, 

 are the twelve thoracic ganglia, corresponding to the twelve ribs. The 

 great semilunar ganglia, the largest of all and sometimes called the ab- 

 dominal brain, are in the abdomen, by the side of the cceliac axis. In 

 the lumbar region, in front of the spinal column, are the four lumbar 

 ganglia. In front of the sacrum are the four or five sacral, or pelvic 

 ganglia ; and finally, in front of the coccyx, is a small single ganglion, 

 the last of the sympathetic chain, called the ganglion impar. Thus, the 

 sympathetic cord, as it is sometimes called, consists of twenty-eight to 

 thirty ganglia on either side, terminating below in a single ganglion. 



Cranial Ganglia. The ophthalmic, lenticular, or ciliary ganglion is 

 situated deeply in the orbit, is of a reddish color and about the size of 

 a pin's-head. It receives a motor branch from the third pair and sensory 

 filaments from the nasal branch of the ophthalmic division of the fifth. It 

 also is connected with the cavernous plexus and with Meckel's gan- 

 glion. Its so-called motor and sensory roots from the third and the 

 fifth pair have already 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 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 relate mainly to the action of 

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

 anatomical relations, leaving its function to be taken up in connection 

 with the physiology of vision. 



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

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

 in the spheno-maxillary fossa, near the spheno-palatine foramen. It 

 receives a motor 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 distri- 

 bution. Two or three small 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 sends also a short 

 branch of a reddish gray color to the carotid plexus. 



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



