258 SECRETION OF SALIVA. [BOOK n. 



of saliva may still be obtained by adequate stimulation of various 

 afferent nerves ; when the medulla is destroyed no such action is 

 possible. And a flow of saliva may be produced by direct stimu- 

 lation of the medulla itself. When a flow of saliva is excited by 

 ideas, or by emotions, the nervous processes begin in the higher 

 parts of the brain, and descend thence to the medulla before they 



FIG. 48. DIAGRAMMATIC KEPRESENTATION OF THE SUBMAXILLARY GLAND OF THE Doa 

 WITH ITS NERVES AND BLOOD-VESSELS. 



(This is not intended to illustrate the exact anatomical relations of the several 

 structures.) 



sm. gld. The submaxillary gland, into the duct (sm. d.) of which a cannula has 

 been tied. The sublingual gland and duct are not shewn. 



n. l.,n.l'. The lingual branch nerve, ch. t.,ch. t'. The chorda tympani, pro- 

 ceeding from the facial nerve, becoming conjoined with the lingual at n.l' and after- 

 wards diverging and passing to the gland along the duct. 



sm. (jl. The submaxillary ganglion with its several roots, n. I. The lingual 

 proceeding to the tongue. 



a. car. The carotid artery, two branches of which, a. sm. a. and r. sm. p., pass to 

 the anterior and posterior parts of the gland, v. sm. the anterior and posterior veins 

 from the gland, falling into v. j. the jugular vein. 



v. sym. The conjoined vagus and sympathetic trunks. 



gl. cer. s. The super-cervical ganglion, two branches of which forming a plexus 

 (a.f.) over the facial artery, are distributed (n. sym. sm.) along the two glandular 

 arteries to the anterior and posterior portions of the gland. 



The arrows indicate the direction taken by the nervous impulses during reflex 

 stimulation of the gland. They ascend to the brain by the lingual and descend by 

 the chorda tympani. 



give rise to distinctly efferent impulses ; and it would appear that 

 these higher parts of the brain are called into action when a flow 

 of saliva is excited by distinct sensations of taste. 



