CHAP, iv.] THE VASCULAR MECHANISM. 



311 



sympathetic, Fig. 59 v. sym. (in the dog, in which the effects which 

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



n.sym.sm. 



FlG. 59. DlAGKAMMATIC BEPRESENTATION OF THE SUBMAXILLARY GLAND OF THE DoG 



WITH ITS NERVES 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. 1., n. I'. The lingual 

 branch of the fifth nerve, the part n. 1. 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, g. 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. 



sympathetic are enclosed in a common sheath so as to form what 

 appears to be a single trunk), which reach the gland in company 

 with the arteries supplying the gland (n. sym. sm.). On the 

 other hand it receives fibres from a small nerve called the chorda 

 tympani (ch. t.), which, springing from the 7th cranial (facial) nerve, 

 crosses the tympanum of the ear (hence the name) and, joining 

 the lingual branch of the 5th nerve, runs for some distance in 



