SYMPATHETIC NERVE.— The term sympathetic nerve is applied to denote a series of ganglia arranged alon,,c, each side of the spinal column, connected by intermediate bands of nerve fibres, so as to present the form of two gangliated cords. These extend from the upper part of the cervical rerrion to the lower extremity of the sacrum where the cords of opposite sides are united' in a single ganglion or plexus situated in front of the coccyx. The ganglia in each cord correspond in number to the vertebrx, except in the cer vical region, where only three ganglia com monly exist. The gangliated cord of either side forms communications with all the cor responding spinal nerves along its course. Branches are also sent upwards from the superior cervical ganglion into the head which communicate with nearly all the cranial nerves, and la ith which several small ganglia, arranged in different parts of the skull, are connected. From the gangliated cords branches also pass inwards for the supply of the bloodvessels, as well as to almost all the different viscera in the body. These branches are remarkable for their tendency to form plexuses, from which subsidiary branches are sent off to the various viscera in their vicinity. Connected with these plexuses, as well as with the branches which pass off from them, are nu merous ganglia of different sizes.
This nerve has been variously named by authors. The older anatomists described it under the name of the great intercostal nerve. From the fact of its being chiefly dis tributed to the viscera belonging to the cir culatory, digestive and generative systems, it was termed by Chaussier the trisplanchnic nerve ; and under the supposition that it alone influences the organic processes, it was termed by Bichat the nervous system of organic life. The name sympathetic, or great sympathetic, was given it by Winslow, from its being be lieved to be the channel through which are effected the different sympathies sometimes found to exist between distant organs when in a morbid condition.
For the sake of description the sympa thetic may be regarded as consisting of two portions ; the one corresponding to the right and left gangliated cords situated on each side of the vertebral column, the other to the dif ferent plexuses occurring on the branches which are sent inwards for the supply of the viscera and bloodvessels. It is commonly further subdivided into a cervical, thoracic, lumbar, and sacral portion. In the following account of its descriptive anatomy it is pro posed to describe, 1st, the gangliated cord of the sympathetic, and 2nd the different plexuses formed by its branches in the several regions of the body already specified.
I. Cervical Portion of the Gangliated Cord.— The cervical portion of each gangliated cord lies in front of the vertebral column, separated from it by the rectus capitis anticus major and longus colli muscles. It is situated behind the internal and common carotid arteries, the internal jugular vein, and pneutnogastric nerve. It presents commonly but three ganglia, named, according to their situation, superior, middle, and inferior.
1. The superior cervical ganglion is situated at the upper and lateral part of the neck, in front of the transverse processes of the second and third cervical vertebm, upon the rectus capitis anticus major muscle, behind and to the inner side of the internal carotid artery and the pneumogastric and glossopharyngeal nerves, with the sheath of which it is more or less intimately connected by some cellular tissue. It is the largest of the ganglia in the sy-rnpathetic cord ; it varies considerably in its form and size. In g,eneral it presents an elongated oval, or spindle-shape, and mea sures from 1 to 8 lines in length, 2 to 3 in breadth, and about It in thickness. Accord ing to Flourens it is generally bifurcated at its lower extremity, and frequently presents a constriction about its middle which appears to divide it into an upper and lower portion. The branches connected with this ganglion are the following: (a) Onnnzunicating branches pass between it and the three or four upper cervical nerves. They vary in number, and are connected with the posterior aspect of the ganglion. It also forms communications with the pneumo gastric, hypoglossal, and glossopharyngeal nerves. The branch of communication with the ninth, or hypoglossal nerve, consisting of one or two delicate filaments, joins it near the base of the skull. This communication is regarded by Scemmering, Cloquet, Hirzel and others as very rarely existing. In twelve bo dies examined by the latter, he found it pre sent only twice. Arnold, Longet and others regard the communication as constant. The communication with the pneumogastric nerve is twofold. One small branch passes between the superior cervical ganglion itself and the ganglion on the trunk of the vagus; another branch, also of small size, passes upwards from the a.scending branch of the superior cervical ganglion, and divides at the base of the skull into two filaments, one of which becomes con nected with the ganglion of the root of the pneumogastric, while the other terminates in the petrosal ganglion of the glossopharyngeal nerve.