THE SYMPATHETIC NERVE. 447 



The structure of all these ganglia appears to be essentially 

 similar, all containing 1st, nerve-fibres traversing them ; 

 2dly, nerve-fibres originating in them ; 3dly, nerve- or ganglion- 

 corpuscles, giving origin to these fibres ; and 4thly, other cor- 

 puscles that appear free. And in the trunk, and thence pro- 

 ceeding branches of the sympathetic, there appear to be al- 

 ways 1st, fibres which arise in its own ganglia ; 2dly, fibres 

 derived from the ganglia of the cerebral and spinal nerves ; 

 3dly, fibres derived from the brain and spinal cord and trans- 

 mitted through the roots of their nerves. The spinal cord, 

 indeed, appears to furnish a large source of the fibres of the 

 sympathetic nerve. 



Respecting the course of the filaments belonging to the sym- 

 pathetic, the following appears to have been determined. Of 

 the filaments derived from the ganglia on the cerebral nerves, 

 some may pass towards the brain ; for, in the trunks of the 

 nerves, between the ganglia and the brain, fine filaments like 

 those of the sympathetic are found. But these may be pro- 

 ceeding from the brain to the ganglia ; and, on the whole, it is 

 probable that nearly all the filaments originating in the 

 ganglia or cerebral nerves, go out towards the tissues and or- 

 gans to be supplied, some of them being centrifugal, some cen- 

 tripetal ; so that each ganglion with its outgoing filaments may 

 form a kind of special nervous system appropriated to the 

 part in which its filaments are placed. Such, for example, 

 may be the ophthalmic ganglion with the ciliary nerves, con- 

 nected with the brain and the rest of the sympathetic system 

 by the branches of the third, fifth, and sympathetic nerves 

 that form its roots, yet, by filaments of its own, controlling in 

 some mode and degree, the processes in the interior of the eye. 



Of the fibres that arise in the spinal ganglia, some appear 

 to pass into the posterior branches of the spinal nerves, and 

 to be distributed with them ; the rest pass through the branches 

 by which the spinal nerves communicate with the trunks of 

 the sympathetic, and then entering the sympathetic are disr 

 tributed with its branches to the viscera. With these, also a 



and first cervical nerve ; 13, external laryngeal nerve ; 14, Second cervical nerve loop- 

 ing with first; 15, pharyngeal plexus on inferior constrictor; 16, superior cervical 

 ganglion of sympathetic ; 17, superior cardiac nerve of pneumogastric ; 18, third cer- 

 vical nerve ; 19, thyroid body; 20, fourth cervical nerve ; 21, 21, left recurrent laryn- 

 geal nerve; 22, spinal-accessory, communicating with cervical nerves; 23, trachea; 

 24, middle cervical ganglion of sympathetic ; 25, middle cardiac nerve of pneumo- 

 gastric ; 26, phrenic nerve (cut) ; 27, left carotid artery (cut) ; 28, brachial plexus ; 29, 

 phrenic nerve (cut); 30, inferior cervical ganglion of sympathetic; 31, pulmonary 

 plexus of pneuraogastric ; 32, arch of the thoracic aorta ; 33, cesophageal plexus ; 34, 

 vena azygos superior; 35, vena azygos minor; 36, gangliated cord of sympathetic. 



