DIGESTION 



VJ1 



relation with ganglion cells, whose axons pass out as non-medullated 

 fibres, and, surrounding the external carotid, reach the salivary glands 

 along its branches. Langley has shown, by means of nicotine (p. 182), 

 that the sympathetic fibres for the submaxillary and sublingual, and, 

 indeed, for the head in general in the dog and cat, are connected with 

 nerve-cells in this ganglion, but not between it and their termination, 

 or between it and their origin from the spinal cord. 



Stimulation of the 

 Cranial Fibres. When 

 in a dog a cannula is 

 placed in Wharton's 

 duct, and the saliva 

 collected (p. 456), it is 

 found that stimulation 

 of the peripheral end 

 of the divided chorda 

 causes a brisk flow of 

 watery saliva, and at 

 the same time a dila- 

 tation of the vessels 

 of the gland, which we 

 have already described 

 in dealing with vaso- 

 motor nerves (p. 179). 

 Notwithstanding the 

 vaso - dilatation, the 

 volume of the gland 

 is in general dimin- 

 ished, owing to the 

 rapid passage of water 

 into the duct (Bunch). 

 The blood has been 

 shown to lose water in 

 making the circuit of 

 the submaxillary 

 gland during excita- 

 tion of the chorda, 

 but doubtless some 

 of the water of the 

 saliva comes directly 



Fig. 160 Nerves of the Salivary Glands. SM and SL, 

 submaxillary and sublingual glands; P, parotid; 

 V, fifth nerve; VII, facial; GP, glosso-pharyngeal; 

 L. lingual; CT, chorda tympani; CL, chordo-lingual ; 

 D, submaxillary (Wharton's) duct; C, ganglion cell 

 of so-called submaxillary ganglion in the chordo- 

 lingual triangle, connected with a nerve fibre going 

 to sublingual gland; C", ganglion cell in hilus of sub- 

 maxillary gland; SSP, small superficial petrosal 

 branch of the facial; OG, otic ganglion; IM, inferior 

 maxillary division of fifth nerve; AT, auriculo- 

 temporal branch of fifth; JN, Jacobson's nerve; 

 C', gangUon cells in superior cervical ganglion (SG) 

 connected with sympathetic fibres going to parotid, 

 submaxillary and sublingual glands. The figure is 

 schematic. 



from the cells or from 

 the lymph. That the increased secretion is not due merely to the 

 greater blood- supply, and the consequent increase of capillary pres- 

 sure, is shown by the injection of atropine, after which stimulation 

 of the nerve, although it still causes dilatation of the vessels, is not 

 followed by a flow of saliva. This can be shown fully as well by 

 injecting a small quantity of yohimbin into the submaxillary artery. 

 Great dilatation of the vessels is produced, but no saliva is secreted; 



