VASOMOTOR ACTIONS. 215 



existing tonic constriction of the bloodvessels of the ear, though this effect 

 is not so constant or striking as that of stimulation. 



153. 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. 78, v. sym. (in the dog, in which 

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



FIG. 78. 



v.sym. 



f sn.sym.f. n.sym.sm. 



Diagrammatic Representation of the Submaxillary Gland of the Dog, with its Nerves and 

 Bloodvessels. The dissection has been on an animal lying on its back, but since all the parts 

 shown 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. Thesnbmaxillary gland, into the duct (sin. d.) of which a canula has been tied. The 

 sublingual gland and duct are not shown. n.l., n.l'. The lingual branch of the fifth nerve, the 

 part n.l. is going to the tongue, ch.t., ch.t'., ch.t". The chorda tympani. The part ch.t". is pro- 

 ceeding from the facial nerve ; at ch. V. it becomes conjoined with the lingual n.l'., and afterward 

 diverging passes as ch. t. to the gland along the duct; the continuation of the nerve in company 

 with the lingual n.l. is not shown, 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. sm. The anterior and posterior veins from the gland, falling 

 into v.j., the jugular vein. v. sym. The conjoined vagus and sympathetic trunks, g. cer. s. The 

 upper cervical ganglion, two branches of which, forming a plexus (a./.) 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 sup- 

 plying 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 

 seventh cranial (facial) nerve, crosses the tympanum of the ear (hence the 

 name) and, joining the lingual branch of the fifth nerve, runs for some dis- 

 tance in company with that nerve, and then ends partly on the tongue, 

 and partly in a small nerve which, leaving the lingual nerve before reach- 

 ing the tongue, runs along the duct of the submaxillary gland, and is lost in 

 the substance of the gland ; a small branch is also given off to the sub- 

 lingual gland. 



