SALIVARY GLANDS 75 



of the blood-vessels, and influence secretion indirectly only by 

 increasing or diminishing the amount of blood going to the 

 glands. The secretory fibers exert their influence directly upon 

 the gland cells. It is claimed also that the secretory fibers are 

 divided into sets controlling the production of the energy-yielding 

 constituents and sets controlling the production of water and salts. 



The parotid gland receives its cerebro-spinal fibers through a 

 branch of the fifth nerve, but when they are traced backward it 

 can be shown that they are in the tympanic branch of the ninth, 

 and pass from this branch to the small superficial petrosal nerve 

 and thence to the optic ganglion from which ganglion they 

 run to the parotid gland by way of the auricula-temporal branch 

 of the third division of the fifth. The cervical sympathetic also 

 sends fibers to this gland. 



The submaxillary and sublingual glands are supplied by the 

 same nerves. Their cerebro-spinal fibers leave the brain by 

 way of the facial, follow the chorda tympani as far as a short 

 distance beyond its junction with the lingual nerve, and then 

 leave it to reach the submaxillary ganglion and run thence to the 

 submaxillary and sublingual glands. These glands receive 

 sympathetic fibers from the superior cervical ganglion. 



Influence of Nerve Supply. Taking the parotid as an ex- 

 ample, it is found that stimulation of its cerebro-spinal fibers 

 produces an abundant watery flow of saliva; the gland becomes 

 decidedly redder, pulsation is sometimes apparent, and it is 

 evident that the amount of blood is locally increased. When 

 the sympathetic supply of the parotid is stimulated, the secretion 

 is inhibited or reduced to a minimum, the gland becomes pale 

 and the amount of blood in it is evidently diminished. 



Similar corresponding results are occasioned in the submax- 

 illary and sublingual glands by stimulation of the chorda tympani 

 and the sympathetic fibers. 



It would seem at first, in the light of the vascular changes 

 accompanying stimulation of the two supplies to all these glands, 



