The Sympathetic Nerve. 



THE Sympathetic Nerve is eo called from the opinion entertained that through 

 it is produced a sympathy between the affections of distant organs. It consists 

 of a series of ganglia, connected together by intervening cords, extending on 

 each side of the vertebral column from the base of the skull to the coccyx. It 

 may, moreover, be traced up into the head, where the ganglia (which are all in 

 connection with the fifth cranial nerve) occupy spaces between the cranial and 

 facial bones. These two gangliated cords lie parallel with one another as far 

 as the sacrum, on which bone they converge, communicating together through 

 a single ganglion (ganglion impar), placed in front of the coccyx. Some 

 anatomists also state that the two cords are joined at their cephalic extremity, 

 through a small ganglion (the ganglion of Eibes), situated upon the anterior 

 communicating artery. Moreover, the chains of opposite sides communicate 

 between these two extremities in several parts, by means of the nervous cords 

 that arise from them. 



The ganglia are somewhat less numerous than the vertebras: thus there are 

 only three in the cervical region, twelve in the dorsal, four in the lumbar, five 

 in the sacral, and one in the coccygeal. 



The sympathetic nerve, for convenience of description, may be divided into 

 several parts, according to the position occupied by each; and the number 

 of ganglia of which each part is composed, may be thus arranged: 



Cephalic portion . . 4 ganglia. 

 Cervical " 3 " 



Dorsal " . . 12 " 



Lumbar " 4 " 



Sacral " 5 " 



Coccygeal " 1 " 



Each ganglion may be regarded as a distinct centre, from or to which 

 branches pass in various directions. These branches may be thus arranged: 

 1. Branches of communication between the ganglia. 2. Branches of commu- 

 nication with the cerebral or spinal nerves. 3. Primary branches passing to be 

 distributed to the arteries in the vicinity of the ganglia, and to the viscera, or 

 proceeding to other ganglia placed in the thorax, abdomen, or pelvis. 



1. The branches of communication between the ganglia are composed of gray 

 and white nerve-fibres, the latter being continuous with those fibres of the 

 spinal nerves which pass to the ganglia. 



2. The branches of communication between the ganglia and the cerebral or 

 spinal nerves also consist of a white and a gray portion; the former proceeding 

 from the .spinal nerve to the ganglion, the latter passing from the ganglion to 

 the spinal nerve. 



3. The primary branches of distribution also consist of two kinds of nerve- 

 fibres, the sympathetic and spinal. They have a remarkable tendency to form 

 intricate plexuses, which encircle the bloodvessels, and are conducted by them 

 to the viscera. The greater number, however, of these branches pass to a series 

 of visceral ganglia: these are ganglionic masses, of variable size, situated in the 

 large cavities of the trunk, the thorax, and abdomen; and are connected with 

 the roots of the great arteries of the viscera. These ganglia are single and 

 unsymmetrical, and are called the cardiac and semilunar. From these visceral 

 ganglia numerous plexuses of nerves are derived, which entwine round the 

 bloodvessels, and are conducted l?y them to the viscera. 



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