624 SYMPATHETIC AND OTHER SYSTEMS OF NERVES 



speaking, we may say that all parts of the skin and mucous membrane, 

 which receive their sole sensory supply from the fifth nerve, receive 

 their sympathetic supply also by way of the fifth nerve. Sympathetic 

 fibres pass to the posterior part of the tongue, the pharynx, and the 

 larynx, by way of the glosso-pharyngeal nerve, the pharyngeal and 

 superior laryngeal branches of the vagus. The tongue receives fibres by 

 way of the hypoglossal, but they are few, for the superior cervical 

 ganglion has no great influence on the vessels of the tongue. 



The ear x receives sympathetic fibres by more than one route, and 

 there are considerable differences in different animals. In the cat, the 

 grey rami, running from the superior cervical ganglion to the first three 

 cervical nerves, contain fibres which accompany the cutaneous branches 

 of these nerves, and thus run to the ear, the occipital region of the 

 head, and the upper part of the neck. The anterior branches of the 

 superior cervical ganglion also contain vasomotor fibres for the ear, but 

 by what course they reach their destination is not known. In the 

 rabbit most of the fibres for the ear are contained in the strand which 

 runs from the superior cervical ganglion to the external carotid, and 

 they follow the branch of the artery which runs to the ear. These 

 fibres, on stimulation, cause contraction of the whole of the central artery, 

 but the effect is sometimes slight at the tip of the ear. As in the cat, 

 some fibres run in the anterior strands of the ganglia, chiefly to the basal 

 third of the ear. It may be mentioned that in the rabbit vasomotor 

 fibres commonly run to the ear from the ganglion stellatum 2 by way of 

 the ramus vertebralis and third cervical nerve ; these, on stimulation, 

 cause contraction, chiefly at the tip of the ear, 3 though the contraction 

 spreads a variable distance towards the base. In the dog most of the 

 vasomotor fibres for the ear run by the anterior branches of the 

 superior cervical ganglion, their further course being unknown, and some 

 pass by the branch to the external carotid artery. 



The sympathetic fibres to the large salivary glands, pass by the 

 strand which runs to the external carotid, and reach the glands by way 

 of their arteries. 



Three bundles of post-ganglionic fibres from the superior cervical 

 ganglion remain for mention. There is that which accompanies the 

 internal carotid ; it would naturally be supposed to convey vasomotor 

 fibres to the vessels of the brain, but this view, as we have said, is con- 

 tested. And there are two bundles, one passing to the third and the 

 other to the sixth cranial nerve, these might be supposed to convey 

 vasomotor fibres to the vessels of the eye muscles, but so far experi- 

 ments have not shown that they do so. 



The general scheme of the distribution of the post-ganglionic fibres 

 of the superior cervical ganglion appears then to be, that those which 

 run to skin and mucous membrane accompany the cranial and cervical 

 sensory fibres running to the skin and mucous membrane, and that those 

 which run to deep visceral structures — the salivary glands — accompany 

 the arteries. There is, however, in the rabbit the striking exception, 

 that vasomotor fibres run to the ear by the artery. And this, together 



1 Morat, Arch, dephysiol. norm, et path., Paris, 1891, p. 87 ; Langley, " Proc. Physiol. 

 Soc," p. ii., Journ. Physio/., Cambridge and London, 1893, vol. xiv. 



" Fletcher, Journ. Physiol., Cambridge and London, 1898, vol. xxii. p. 259. 



3 The vasomotor action of the great auricular nerve was first described by Schifl', and its 

 local action by Loven, Arb. a. d. physio/. Ansf. zu Leipzig, 1866. An anatomical account 

 of the nervous supply of the ear of the rabbit is given in this paper. 



