THE SYMPATHETIC NERVOUS SYSTEM 351 



The my enteric plexus (of Auerbach) and the submucous plexus (of Meissner), 

 located within the walls of the stomach and intestines, receive filaments from 

 the gastric and mesenteric divisions of the celiac plexus. They also receive 

 fibers from the vagus either directly, as in the case of the stomach, or indirectly 

 through the celiac plexus (Fig. 257). Unfortunately, very little is known con- 

 cerning the synaptic relations established in the ganglia of these plexuses. Ac- 

 cording to Langley, the postganglionic fibers from the celiac ganglia run through 

 these plexuses without interruption and end in the muscular coats and glands 

 of the gastro-intestinal tract. The preganglionic fibers from the vagus probably 

 end in synaptic relation to cells in these small ganglia; and the axons of these 

 cells serve as postganglionic fibers, relaying the impulses from the vagus to the 

 glands and muscular tissue. As was indicated in a preceding paragraph, the 

 enteric plexuses must also contain a mechanism for purely local reactions, since 

 peristalsis can be set up by distention in an excised portion of the gut. But 

 as yet we are entirely ignorant as to what that mechanism may be. 



The hypogastric plexus is formed by strands which run into the pelvis from 

 the lower end of the aortic plexus and are joined by the visceral branches of the 

 second, third, and fourth sacral nerves and by branches from the sympathetic 

 trunk (Figs. 248, 257). As the hypogastric plexus enters the pelvis it splits into 

 two parts, which lie on either side of the rectum and are sometimes called the 

 pelvic plexuses. From these plexuses branches are supplied to the pelvic vis- 

 cera and the external genitalia. 



The Cephalic Ganglionated Plexus. In close topographic relation to the 

 branches of the fifth cranial nerve are four sympathetic ganglia, known as the 

 ciliary, sphenopalatine, otic, and submaxillary ganglia. Each of these is con- 

 nected with the superior cervical sympathetic ganglion by filaments derived 

 from the plexuses on the internal and external carotid arteries and their branches 

 (Fig. 257). These filaments are designated in descriptive anatomy as the sym- 

 pathetic roots of the ganglia. Each ganglion receives preganglionic fibers from 

 one of the cranial nerves by way of what is usually designated as its motor root 

 (Fig. 257). Thus the ciliary ganglion receives fibers from the oculomotor nerve; 

 the sphenopalatine ganglion receives fibers from the facial nerve by way of the 

 great superficial petrosal nerve and the nerve of the pterygoid canal; the otic 

 ganglion receives fibers from the glossopharyngeal nerve (Miiller and Dahl, 1910) ; 

 and the submaxillary ganglion receives fibers from the facial nerve by way of 

 the nervus intermedius and the lingual nerve. Postganglionic fibers arising 

 in these ganglia are distributed to the structures of the head. From the ciliary 



