GREAT SYMPATHETIC. 



91 



nervous cords, proceeding from it, are distinguished by a simple fasci- 

 culus or single root. All these are simple in their origins ; irregular 

 in their distribution ; and deficient in that symmetry which characterizes 

 those of the first class. They are superadded to the original class; 

 and correspond to the number and complication of the superadded 

 organs. Of these, there are the third, fourth, and sixth, distributed to 

 the eye ; the seventh, to the face ; the ninth, to the tongue ; the glosso- 

 pharyngeal, to the pharynx ; the vagus, to the larynx, heart, lungs, 

 and stomach ; the phrenic, to the diaphragm ; the spinal accessory, to 

 the muscles of the shoulders ; and the external respiratory, to the out- 

 side of the chest. The reason of the seeming confusion in this latter 

 class is to be looked for in the complication of the superadded apparatus 

 of respiration, and in the variety of offices it has to perform in the 

 higher classes of animals. 



The accompanying plate exhibits, in one view, the nerves destined to 

 move the muscles in all the varieties of respiration, speech, and facial 

 expression. 



In the plate of regular or symmetrical nerves, 



A is the cerebrum, B, the cerebellum, Fig. 22. 



C C, the crura cerebri, D D, the crura cere- 

 belli, E E E, the spinal marrow. 



1 1. Branches of the fifth pair, arising from 

 the union of the crura cerebri and crura 

 cerebelli, and having a ganglion at the root. 



2 2. Branches of the sub-occipital nerves, 

 which have double origins and a ganglion. 



3 3. Branches of the four inferior cervical 

 nerves, and of the first dorsal, forming the 

 axillary plexus. The origins of these nerves 

 are similar to those of the fifth and of the 

 sub-occipital. 4444. Branches of the 

 dorsal nerves, which also arise in the same 

 manner. 5 5. The lumbar nerves. 6 6. The 

 sacral nerves. 



So much for the anatomy of 

 two great portions of the nervous 

 system. There remains to be 

 considered a third, and by no 

 means the least interesting or 

 important. 



4. 0-reat Sympathetic. This 

 nerve, called also trisplanchnic, 

 splanchnic, ganglionic, great 

 intercostal, vegetative, and or- 

 ganic, is constituted of a series 

 of ganglions, joined to each other 



by a nervous trunk, and extending Roots of a Dorsal Spinal Nerve, and its union with 



down the side of the spine, from Sympathetic. 



thf* hnlf> n~F tVip nrn-mnm ir\ tlia e> c. Anterior fissure of the spinal cord, a. Anterior 



. tne cranium to tne root . PI Posterior rootj with \ ts gang i ion . a <. A nte- 



OS COCCVSriS Or lowest bone. It rior branch - P'- Posterior branch, s. Sympathetic. 

 . . ,, , n i e - Its double junction with the anterior branch of the 



Communicates With each of the spinal nerve by a white and a gray filament. 



spinal nerves, and with several 



