CHAP, iv.] THE VASCULAR MECHANISM. 



267 



existing tonic constriction of the blood vessels of the ear, though 

 the effect of section is not so constant or striking as that of 

 stimulation. 



145. We must now turn to another case. In dealing with 

 digestion we shall have to study the submaxillary salivary gland. 

 We may for the present simply say that this is a glandular mass 

 well supplied with blood vessels, and possessing a double nervous 

 supply. On the one hand it receives fibres from the cervical 

 sympathetic, Fig. 73 v. sym. (in the dog, in which the effects which 

 we are about to describe are best seen, the vagus and cervical 



cTi.t' 



FIG. 73. DIAGRAMMATIC REPRESENTATION OF THE SUBMAXILLARY GLAND OP 

 THE DOG WITH ITS NERVE AND BLOOD VESSELS. 



(The dissection has been made on an animal lying on its back, but since all the 

 parts shewn in the figure cannot be seen from any one point of view, the figure does 

 not give 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. I., n. I'. The lingual 

 branch of the fifth nerve, the part n. I. is going to the tongue. ch. t., ch. t'., ch. t". 

 The chorda tympani The part ch. t". is proceeding from the facial nerve ; at ch. t'. 

 it becomes conjoined with the lingual n i and afterwards diverging passes as ch. t. 

 to the gland along the duct ; the continuation of the nerve in company with the 

 lingual n. I. is not shewn, sm. gl. The submaxillary ganglion with its several 

 roots, a. car. The carotid artery, two small branches of which, a. sm. a. and r. sm. p., 

 pass to the anterior and posterior parts of the gland, v.s.m. The anterior and pos- 

 terior veins from the gland, falling into v. j. the jugular vein. v. sym. The con- 

 joined vagus and sympathetic trunks, q. cer. s. The upper 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. 



