194 HUMAN PHYSIOLOGY. 



beneath the foramen ovale; receives a motor filament from the facial and 

 sensor filaments from the glossopharyngeal and fifth nerves; sends filaments 

 to the mucous membrane of the tympanic cavity and to the tensor tympani 

 muscle. 



4. The submaxillary ganglion, situated in the submaxillary gland, receives 

 filaments from the chorda tympani, sensor filaments from the lingual 

 branch of the fifth nerve, and filaments from the sympathetic. The chorda 

 tympani nerve supplies vaso-dilatator and secretor fibers to the submaxillary 

 and sublingual glands. The fifth nerve endows the glands with sensibility, 

 while the sympathetic supplies vaso-constrictor fibers to the blood-vessels of 

 the glands. 



Cervical Ganglia. 



The superior cervical ganglion is fusiform in shape, of a grayish-red color, 

 and situated opposite the second and third cervical vertebrae; it sends branches 

 to form the carotid and cavernous plexuses, which branches follow the course 

 of the carotid arteries to their distribution; also sends branches to join the 

 glossopharyngeal and pneumogastric, to form the pharyngeal plexus. 



The middle cervical ganglion, the smallest of the three, is occasionally 

 absent; it is situated opposite the fifth cervical vertebra; sends branches to 

 the superior and inferior cervical ganglia and to the thyroid artery. 



The inferior cervical ganglion, irregular in form, is situated opposite the 

 last cervical vertebra; it is frequently united with the first thoracic ganglion. 



The superior, middle, and inferior cardiac nerves, arising from these cervical 

 ganglia, pass downward and forward to form the deep and superficial cardiac 

 plexuses located at the bifurcation of the trachea, from which branches are 

 distributed to the heart, coronary arteries, etc. 



The thoracic ganglia are usually twelve in number, and are placed against 

 the heads of the ribs behind the pleura; they are small in size and gray in 

 color; they communicate with the cerebrospinal nerves by two filaments, one 

 of which is white, the other gray. 



The great splanchnic nerve is formed by the union of branches from the 

 sixth, seventh, eighth, and ninth ganglia; it passes through the diaphragm to 

 the semilunar ganglion. 



The lesser splanchnic nerve is formed by the union of filaments from the 

 tenth and eleventh ganglia, and is distributed to the celiac plexus. 



The renal splanchnic nerve arises from the last thoracic ganglion and 

 terminates in the renal plexus. 



The semilunar ganglia, the largest of the sympathetic system, are situated 

 by the side of the celiac axis; they send radiating branches to form the solar 



