. PAR VAGUM. | 
extent with several of the other cerebro-spinal 
nerves, as the spinal accessory, the glosso- 
pharyngeal, the hypo-glossal, the portio dura, 
the two superior cervical, and sometimes with 
some of the lower cervicals. The vagi are 
very extensively ramified upon the internal 
tegumentary membrane, as the mucous mem- 
brane of the pharynx, larynx, «esophagus, sto- 
mach, trachea, and lungs, and send only one 
small branch, viz. the ramus auricularis, to 
the external tegumentary membrane. Many 
of its branches are distributed upon the mus- 
cular fibres surrounding the upper part of the 
digestive and respiratory tubes. 
Physiology of the nervus vagus.—From the 
distribution of this nerve in so many of the 
most important organs in the body which it is 
impossible to insulate, or prevent their mutual 
actions and reactions upon each other, and 
from its numerous and intimate connections 
with several other nerves, investigations into its 
physiology are beset with unusual difficulties, 
As, however, its lesions are attended by the 
most serious derangements of the respiratory 
and digestive organs, and as a knowledge of 
its functions bears in a prominent manner upon 
many interesting questions both in special and 
general physiology, it has naturally attracted 
the frequent attention of the physiologist, and 
has been made the subject of numerous experi- 
mental investigations. 
Do the roots of the vagus contain any motor 
filaments?—No one can for a moment doubt 
that the trunk of the vagus, in its course down 
the neck, does contain motor filaments, but 
there is every reason to believe that it derives 
at least the greater part of these from the spinal 
_ accessory. From the resemblance of the vagus 
and spinal accessory as they lie in the foramen 
lacerum posterius to the anterior and posterior 
roots of a spinal nerve,—the vagus with its supe-~ 
| rior ganglion corresponding to the posterior, 
| and the spinal accessory to the anterior root,— 
| many anatomists and physiologists have of late 
maintained that the roots of the vagus, like the 
| posterior roots of the “ng nerve, contain no 
_ motiferous filaments. It is scarcely necessary 
hi to add, that the junction of the internal branch 
_ of the accessory and the vagus immediately 
ty beyond the superior ganglion of the latter, in- 
| creases still further this resemblance between 
_ these and a spinal nerve. This opinion has 
_ been maintained on anatomical considerations 
t 
f 
| 
_alone, by Arnold, Scarpa, and Bendz,* and 
has been further strengthened by the experi- 
- ments of Bischoff,+ Valentin,t and Longet.§ 
* Tractatus de Connexu inter Nervum Vagum 
et Accessorium Willisii, Haunie, 1836. According 
to Miiller, this idea of the resemblance of the ana- 
tomical arrangement of the vagus and accessory to 
a spinal nerve had previously suggested itself to 
_ Gorres in his Exposition der Physiologie, 1809. 
+ Nervi Accessorij Willisii Anat. et Phys. 1832. 
_by experiment that the root of the vagus does con- 
tain motor filaments. } 
_ $ De Functionibus Nerv. Cereb. et Nerv. Sym- 
path. Caput xi. Berne, 1839. 
_ § Recherches Experimentales sur les Functions 
des Nerfs, des Muscles du Larynx, &c. p.31, Paris, 
pay 
+ aia 
Bischoff, however, has more lately satisfied himself - 
894 
It is on the.other hand maintained, that this 
opinion is too exclusive, and that, though there 
can be no doubt of the greater part of the fila- 
ments of the roots of the vagus being incident 
and sensiferous, yet they do contain some mo- 
tiferous filaments. We have seen that, proba- 
bly both in man and in some of the other 
mammalia, a few of the filaments of the vagus 
do not pass through its superior ganglion, and 
consequently the anatomical argument is not 
so conclusive as it at first appears to be. An 
examination of the experimental proof adduced 
in favour of these two opinions shews that the 
former is chiefly founded upon negative, and 
the latter upon positive evidence. Miiller* 
saw muscular movements of the pharynx follow 
excitation of the roots of the vagus within the 
cranium ; but from having neglected some pre- 
cautions in the performance of the experiment, 
he himself is not disposed to attach to it much 
weight. I have related some experiments in 
which I observed muscular movements in the 
pharynx, larynx, and esophagus, from irritation 
of the vagus within the cranium, on the dog 
immediately after death.t Volkmann has per- 
formed similar experiments upon calves, sheep, 
goats, and cats, and perceived muscular con- 
tractions in the levator palati, azygos uvule, 
the superior and inferior constrictor muscles of 
the pharynx, the palato-pharyngeus, and crico- 
thyroid.{ The experiments of Stilling,§ Wag- 
ner,|| Van Kempen,{j Hein,** and Bernard+t+ 
are also all in favour of the opinion that the 
root of the vagus contains motor filaments. 
1841, and Anatomie et Physiologie du Systéme 
Nerveux, &c. tom. ii. p. 262. Paris, 1842. 
* Elements of Physiology, translated by Baly, 
pp. 703-4. Second edition. 
+ Edinburgh Medical and Surgical Journal, 1838. 
$ Miiller’s Archives, p. 493, for 1840. Volk- 
mann expressly states that these muscular contrac- 
tions were also observed on irritating the vagus 
within the cranium in the calf, though in that ani- 
mal all the filaments of the vagus appeared to him 
to pass through its superior ganglion. 
§ Stilling states that he saw movements of the 
pharynx, the glottis, and the stomach in two cats, 
on exciting the roots of the vagus within the cra- 
nium. Vide Bischoff’s Bericht tiber die Fort- 
schritte der Physiologie in Jahre 1842, in Miiller’s 
Archives for 1843. Heft vi. p. 154. 
| Lehrbuch der Physiologie. Dritte Abtheilung, 
S. 329. Leipzig, 1842. 
{| Van Kempen observed contractions of the con- 
strictors of the pharynx, the palato-glossus, the 
esophagus, and the interior muscles of the larynx. 
Essai Experimental sur la Nature fonctionelle du 
Nerf-pneumogastrique, Louvain, 1842. Vide also 
Rischoff’s Bericht, &c. supra cit. pp. 154-5. Bischoff 
states (p. 155) that he himself observed movements 
of the soft palate, in which the contractions of the 
levator palati muscle were very decided, on the 
irritation of the roots both of the vagus and of the 
accessory. 
** Hein observed contractions in the elevator pa- 
lati, azygos uvule, and palato-pharyngeus, but in 
the. last muscle less frequently than in the two 
former, on irritating the root of the vagus, and the 
same muscles were thrown into contraction by irri- 
tation of the root of the accessory. He also per-~ 
ceived contractions in the stylo-pharyngeus from 
irritetion of the root of the glosso-pharyngeal nerve, 
as in the experiments of Mayo and Volkmann, 
Miiller’s Archives, Heft iii. 1844. S. 297. 
tt Archives Générales de Méd. 1844. 
