612 TEXT-BOOK OF PHYSIOLOGY. 



1. The cervical, which connects the thoracic ganglia with the superior 



cervical ganglion. It is composed mainly of medullated nerve-fibers 

 which are derived originally from the spinal nerves. 



2. The great splanchnic nerve, formed by the union of branches from the fifth 



to the tenth thoracic ganglia. It connects these ganglia with the semi- 

 lunar ganglion. 



3. The small splanchnic nerve, formed by the union of branches from the ninth 



and tenth thoracic ganglia. It connects these ganglia with the solar 

 and renal plexuses. 



THE ANATOMIC RELATIONS OF THE SYMPATHETIC GANGLIA TO 

 VISCERAL STRUCTURES. 



The Vertebral Ganglia. Each ganglion of the vertebral chain gives 

 origin to one or more gray rami communicantes , which pass backward and 

 outward and enter the sheath of the corresponding spinal nerve. In the 

 cervical region, however, where the ganglia do not correspond in number 

 with the cervical spinal nerves, the ganglia give off two or more gray rami. 

 Thus in man the superior cervical ganglion sends branches to the first 

 four cervical nerves. The middle and inferior ganglia send a branch to the 

 fifth and sixth and the seventh and eighth cervical nerves respectively. 

 In the thoracic, lumbar, and sacral regions, the ganglion sends at least one 

 gray ramus into the sheath of the corresponding thoracic, lumbar or sacral 

 nerves. 



As previously stated, the gray rami which thus enter the sheath of the 

 spinal nerve trunks, pass in company with their contained efferent fibers, to 

 the periphery, to be finally distributed to structures in the skin, viz., non- 

 striated muscles of blood-vessels, non-striated muscles of hair-follicles, 

 and epithelium of sweat glands. Experimental investigations have made it 

 apparent that these post-ganglionic fibers may be regarded as having vaso- 

 motor and secretor functions. The blood-vessels and sweat glands of the 

 skin of the neck receive their ganglionic nerve-supply from the superior and 

 middle cervical ganglia; those of the skin of the arm, from the inferior cervical 

 and first thoracic ganglia; those for the skin of the trunk, from the thoracic 

 ganglia; those for the skin of the hip and leg, from the lumbar and upper 

 sacral ganglia; those for the skin of the external genital organs, from the lower 

 sacral ganglia. 



Most if not all the vertebral ganglia give origin, in addition to the gray 

 rami communicantes just alluded to, other branches known as visceral 

 branches or rami viscerates which pass to regions near and remote though 

 their ultimate distribution is not in all instances apparent. 



The superior cervical ganglion gives off from its cephalic extremity two 

 visceral branches, which subsequently divide and subdivide forming the 

 carotid and cavernous plexuses; from these plexuses slender branches follow 

 the course of the more superficial arteries at least, to their terminations, 

 while others pass into the trunks of the trigeminal, abducent, and the superior 

 and deep petrosal branches of the facial nerve, to be distributed to blood- 

 vessels and glands of special regions of the head and face. Still other 

 branches pass down the neck and in their course become associated with 

 corresponding branches from the middle and inferior cervical ganglia. In- 



