The Sympathetic Nerve. 



THE Sympathetic Nerve is so 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 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 Kibes), situated upon the anterior com- 

 municating 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 vertebra ; 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 ganglion. 



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 communication 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 

 ganglia, or 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 

 are derived, which entwine round the bloodvessels, and are conducted by them to 

 the viscera. 



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