GENERAL ARRANGEMENT OF THE SYMPATHETIC SYSTEM. 731 



The general arrangement of the sympathetic ganglia and the distribution of the nerves 

 may be stated, sufficiently for our purposes, very briefly ; still, a knowledge of certain 

 anatomical points is indispensable as an introduction to an intelligent study of the physi- 

 ology of this system. 



In the cranium, are four ganglia; the ophthalmic, the spheno-palatine, the otic, and 

 the submaxillary. In the neck, are the 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, sometimes called the abdominal brain, are 

 in the abdomen, by the side of the crcliac axis. In the lumbar region, in front of the 

 spinal column, are the four, and sometimes five, lumbar ganglia. In front of the sacrum, 

 are the four or five sacral, or pelvic ganglia ; and in front of the coccyx, is a small, single 

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

 as it is sometimes called, consists of from 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 ophthal- 

 mic division of the fifth. It is also connected with the cavernous plexus and with 

 Meckel's ganglion. 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 dis- 

 tribution 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 functions of the ophthalmic ganglion are connected exclusively with the action 

 of the ciliary muscle and iris ; and we shall here merely indicate its anatomical relations, 

 leaving its physiology to be taken up under the head of vision. 



The spheno-palatine ganglion was first described by Meckel and is known as Meckel's 

 ganglion. This is the largest of the cranial ganglia. It is of a triangular shape, reddish 

 in color, and is 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. Its 

 branches of distribution are quite numerous. 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 uvulee 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 motor 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 Eusta- 

 chian tube and to the tensor tympani and tensor palati muscles. Reasoning from the 

 general mode of distribution of the sympathetic filaments, those going to the striated 

 muscles are derived from the facial. It also sends branches to the carotid pU.-xus. 



The submaxillary ganglion, situated on the submaxillary gland, is small, roumK-d, 

 and of a reddish-gray color. It receives motor filaments from the chorda tympad 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, 



