662 SYMPATHETIC AND OTHER SYSTEMS OF NERVES. 



have been given elsewhere. 1 Prevost 2 was the first to obtain evidence of vaso- 

 dilator fibres in the nasal mucous membrane on stimulating the spheno-palatine 

 ganglion. Vulpian 3 found dilator fibres for the vessels of the anterior part of 

 the tongue in the lingual nerve, and for the posterior part in the glosso- 

 pharyngeal nerves. He traced the fibres to the seventh and ninth nerves 

 respectively. 4 Jolyet and Laffont 5 observed flushing in the nasal and parts of 

 the buccal mucous membrane on stimulating the superior maxillary nerve. For 

 further information, see the papers quoted below in the footnotes. 



Fifth nerve. Whether the roots of the fifth nerve have any 

 autonomic fibres must, I think, be regarded as doubtful, They have been 

 said to contain secretory fibres, constrictor and dilator fibres for the pupil, 

 constrictor and dilator fibres for the blood vessels. The view that the 

 fifth nerve has secretory fibres is now practically abandoned. There is 

 no evidence worth considering here that it contains vaso-constrictor 

 fibres. 6 Many observers have advocated the view that the fifth nerve 

 sends constrictor fibres of a peculiar kind to the iris of the rabbit. The 

 chief evidence alleged is that, after atropin has been given and the 

 cervical sympathetic cut, stimulation of the first and second cervical 

 segments of the cord, of the bulb, and of the fifth nerve, causes constric- 

 tion of the pupil. 7 But in the cat and dog the fifth nerve has apparently 

 no action on the iris. 



There is, on the other hand, some evidence for the existence of vaso- 

 dilator fibres in the roots of the fifth. Stimulation of the fifth nerve in 

 the skull with a strong current will cause in the dog vascular dilatation 

 of the mouth, lips, and part of the adjoining skin, as well as dilatation of 

 the pupil. Part of the effect is certainly due to an escape of current to 

 the sympathetic filaments which join the fifth nerve at or near the 

 G-asserian ganglion. This is shown by making the current weaker when 

 there is no longer an effect on the pupil or on the skin of the face. 8 

 Thus a strong current stimulates the sympathetic grey ramus to the 

 fifth in just the same way as we have seen the grey ramus to a spinal 

 nerve can be stimulated (cf. p. 631). The question then is, whether the 

 flushing of the mucous membrane of the mouth, when it alone is obtained 

 by stimulating the roots of the fifth, is also due to an escape of current 

 or not. According to Laffont, y stimulation of the superior maxillary 

 nerve in the dog causes flushing twenty days after extirpation of the 

 superior cervical ganglion, i.e. at a time when the sympathetic fibres in 

 the fifth have degenerated. There still remains the possibility of an 

 escape of current to the spheno-palatine ganglion or to fibres running to 

 it from the seventh or ninth nerve. If Vulpian's statement, that these 

 nerves have no vaso-dilator fibres for the mucous membrane of the 

 cheek and gums, were confirmed, the balance of evidence would be 



1 See art. "The Salivary Glands," this Text-Book, Vol. I. pp. 479-485. 



2 Arch. dephysioL norm, etpath., Paris, 1868, pp. 7 and 207. 



% 3 Compt. rend. Acad. d. sc., Paris, 1873, tome Ixxvi. p. 622 ; ibid., 1875, tome Ixxx. 

 p. 330 ; cf. also Lepine, Arb. a. d. pliysiol. Anst. zu Leipzig, 1870. 



4 Compt. rend. Acad. d. sc., Paris, 1885, tome ci. pp. 851, 981, 1037, 1448. 



5 Ibid., 1879, tome Ixxjcix. p. 1038. 



6 An account of observations on the matter will be found in Tigerstedt's " Physiologic 

 des Kreislaufs," Leipzig, 1893, S. 480, 481. 



7 Cf. Eckhard, Centralbl. f. PhysioL, Leipzig u. Wien, 1892, S. 129 ; Griinhagen, ibid., 

 S. 326; and S. Mayer's account of the earlier observations in Hermann's "Handbuch," 

 Leipzig, 1879, Bd. ii. Th. 1, S. 248-252. 



* Vulpian, Compt. rend. Acad. d. sc., Paris, 1885, tome ci. p. 981. 

 9 Compt. rend. Soc. de biol., Paris, 1880, p. 297. 



