386 



DIGESTION 



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. 180), 

 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. 450), 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. 177). 

 Notwithstanding the 

 vaso - dilatation, the 

 volume of the gland 

 is in general dimin- 

 ished, owing to the 

 rapid passage of water 



L, lingual; CT, chorda tympani; CL, chordo-lingual ; into the duct (Bunch). 

 D, submaxillary (Wharton's) duct; C, ganglion cell The blood has been 



Fig. 100 Nerves of the Salivary Glands. SM and SL, 

 submaxillary and sublingual glands; P, parotid; 

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



of so-called submaxillary ganglion in the chordo- 

 lingual triangle, connected with a neive 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', ganglion cells in superior cervical ganglion (SG) 

 connected with sympathetic fibres going to parotid, 

 submaxillary and sublingual glands. The figure is 

 schematic. 



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 



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. Mere increase of pressure could not 

 in any case of itself account for the secretion, since it has been 



