THE 
VAGUS NERVE 
I N 
THE DOMESTIC CAT 
(Felis clomestica). 
By T. B. ST0WELL>i A.M., Ph.D. 
(Read before the American Philosophical Society, July 15, 1881.) 1881.] 
123 
[Stowell 
The Vagus Nerve in the Domestic Cat (Felis ilomestica) 
By T. B. Stouten, AM., Ph.D. 
(Read before the American Philosophical Society, July 15, 1881.) 
The idea of using the cat as the basis of anatomical study is by no means 
arecentone. Straus-Durckheim’s “AnatomicduChat,” Dr. B. G. Wilder’s 
“ Anatomical Uses of the Cat,” and other papers published by the same 
author since 1877, and Mivart’s recent work on “The Cat,” present the 
general thought with more or less directness. I am not aware, however, 
that any one has made a study of the nerves of the cat in their detailed 
distribution. Having compared the vagus nerve in man, cat, dog, horse, 
ox, sheep, rabbit and frog, I am satisfied that the cat (Felis dornestica) pre- 
sents advantages over all others as a basis for comparative study. I ac- 
cordingly submit the accompanying figures and text to aid students who 
may be disposed to investigate Comparative Neurology. 
The cat, dog, and rabbit were injected with plaster, as recommended by 
Prof. Simon II. Gage, of Cornell University, in a paper published in The 
American Naturalist, vol. xii, p. 717. The figures are semi-diagrammatic; 
they were originally drawn to a scale, natural size; for the purpose of giving 
prominence to certain relations, to ramuli and anastomotic filaments, such 
modifications have been made as seemed necessar}'; where a nerve trunk is 
continuous, with no distinctive characters, it is shortened, e.g., thegastro- 
cardiac portions of the vagus (Fig. 9). The figure of the stomach is re- 
duced one-lialf (Fig. 13). For the sake of simplicity no attempt has been 
made to reproduce plexuses or the terminal ramification of filaments. 
The nomenclature used is largely that advocated by Dr. B. G. Wilder, 
before the American Association for the Advancement of Science, at Boston, 
J880, in a paper entitled “A Partial Revision of the Nomenclature of the- 
Brain,” and in a more detailed communication published in Science, March 
19, and 20, 1881, entitled “A partial Revision of Anatomical Nomencla- 
ture, with especial reference to that of the Brain.” The simplicity and 
perspicuity of the nomenclature commend it alike to the lecture-room and 
the laboratory. 
[In cases wliere it was thought that any possible doubt might arise from using 
the new terminology, the new words are followed by their anthropotomica 
equivalents] 
The vagus nerve (N. vagus; N, pneumogastricus; Pars vaga; Par vagum; 
N. ambulatorius; N. sympathicus medius; Eighth pair, pneumogastric 
branch, Willis; Tenth pair, Sommering and Vicq-d’Azyr) presents the 
following marked characters, viz :— 
General Characters : N. vagus has the most extensive distribution 
and the longest course of the cranial nerves ; in its cephalic region princi- 
pal rami are derived from ganglia ; it forms by its frequent and complex 
anastomoses with N. sympathicus numerous plexuses, hence presents in- 
volved physiological and pathological complications ; its terminal fila- 
PROC. AMER. PHILOS. SOC. XX. 111. P. PRINTED MARCH 8r 1882. Stoweil.] 
124 
[July 15, 
ments supply the muscular substance and the mucous membranes of 
organs ; its development in relation with the development of, notably, the 
heart and adjacent blood-vessels, and the stomach, renders its distribu- 
tion somewhat asymmetrical, necessitating special anatomical study of its 
dextral and sinistral relations, and giving corresponding and distinctive 
physiological and pathological characters ; the relation of this nerve to 
organic life, to the automatic and the reflex phenomena of respiration, 
and to the so-called “inhibitory phenomena” gives importance to its 
study. 
Special anatomical characters: N. vagus and its rami are dis- 
tributed to the most important viscera, at least to viscera most intimately 
related to the functions of organic life, e. g., digestive—pharynx, oesopha- 
gus, stomach, liver, pancreas, intestines ; circulatory—heart, pulmonary 
arteries, pulmonary veins, systemic arteries and veins in the region of the 
heart; respiratory—larynx, trachea, bronchi, substance of lung. 
Special physiological characters: N. vagus is a sensory-motor 
nerve, having both sensitive and motor fibres ; it controls, regulates or 
modifies the movements and the secretory functions of the organs to 
which it is distributed, and upon it depend the sensory phenomena which 
•characterize the respective organs. 
DESCRIPTION : Origin and cervical portion—X. vagus in 
the cat (Felis doniestica) takes its superficial origin from two regions of 
t,lie medulla : by 12-14 filaments from the ventral border of corpus resti- 
forme and the depression line between cp. restiforme and the portion of 
medulla next laterad (Fig. 3, 4),* in a line caudad of (posterior to) 
the origin-filaments of N. glosso-pharyngeus (ninth pair of cranial 
nerves), (Fig. 2, 4), from which nerve it is sometimes separated by a 
small arterial twig of A. cerebellosa inferior ; and by 4-6 filaments imme- 
diately ventrad in the slight depression line ventrad of oliva and cepha- 
lad of the origin-filaments of the spinal portion of N". accessorius (Fig. 2. 
L). The dorsal filaments form a somewhat curved line of superficial 
origin, measuring 3-4 mm. in caudo-cephalic direction, and presenting its 
convexity dorsad (Fig. 2. X) ; the cephalic filaments are most ventral and 
leave the medulla oblongata just caudad of A. cerebellosa inferior—a con- 
siderable branch of A. basilaris at right angles with the main trunk and 
* There is some difficulty in establishing satisfactorily the homologies of the 
medulla. There are reasons for regarding the third nerve tract irom the dor- 
simeson as the homologue of corpus olivarium: this is manifestly not the cp. 
ollvarium of Foster as given in his “ Practical Physiologyit should be noticed 
that the cephalic origin-filaments of N. accessorius become apparent in this 
depression line, while the caudal origin-fllaments appear along the depression 
line venirad of this tract. The elliptical area (Fig. 1, 3) laterad of ventripyra- 
mis (anterior pyramid) and the one still dorso-lateral have relations upon which 
homologies might be based, giving each one the name oliva (corpus olivarium). 
It is not proper in this connection to discuss homologies. I have made this 
allusion in apology for the indeflniteness of description of the origin-line of N. 
'Jagus. Whatever homologies may be established and names assigned, the 
figures (Fig. 3, 4) designate the relation. 1881.] 
125 
[Stowell. 
given off 4-6 mm. cephalad of union of A A. vertebralos. These filaments 
unite about 1 mm. peripherad of their superficial origin into six or seven 
ramuli, which lie ventrad of plexus clioroideus lateralis (Fig. 2, PI. Ch.), 
and blend in foramen jugulare to form a single flattened nerve trunk, X. 
vagus. In the passage through the foramen 0 mm. peripherad of 
its origin. X. vagus is enclosed in common with X. accessorius (XI) in 
a sheath formed by a tubular prolongation of the dura mater and the 
arachnoid membrane, where it is also joined by X. glosso-pharyngeus 
(IX) ; but the sheath of the united XX. vagus (X) and accessorius (XI) 
may be readily dissected from that of X. glosso-pharyngeus (IX), which lies 
ectad and cephalad. Centrad of its foramen of exit—Foramen jugulare, 
(Foramen lacerum-posterius, Lacerum foramen posterius)—and 8-4 mm. 
peripherad of medulla oblongata, X. vagus presents a ganglionic enlarge- 
ment, ganglion jugulare, ganglion of the root. This ganglion is hemi- 
spherical in form, of a grayish color, and measures nearly 2 mm. in diam- 
eter ; it has relations with XX. facialis, glosso-pharyngeus, accessorius 
and sympathicus (Fig. 5, J). 
At G. jugulare, X. vagus is connected by a single twig with the adjacent 
petrous ganglion of X. glosso-pharyngeus (IX) the “ganglion of An- 
dersclv’’ (Fig. 5, Pe.); by a considerable trunk with X. accessorius (Fig. 
6, 10); by ramus auricularis (Fig. 5, 2), with X. facialis (VII), from which 
ramus, a slender ramulus penetrates the petrous bone and joins a branch 
of X. facialis; a portion of the ramus continues across X. facialis to the 
cochlea (Fig. 5, 5), a filament from the auricular branch connects with a 
ganglionic plexus of X. sympathicus, entad of the gangliform plexus of 
X. vagus. 
Plexus The 5 mm. of 1ST. vagus immediately caudad 
of G. jugulare is involved in a somewhat intricate net-work, which seems 
to be allied to plexus gangliformis (Fig. 6., Px. gang.); the apposed trunks 
of XX. glosso-pharyngeus (IX), vagus (X), accessorius (XI) and liypo- 
glossus (XII), are embraced by interlacing filaments of X. sympathicus, 
with which nerve they sustain more or less intimate relations, through 
anastomotic filaments; X. glosso-pharyngeus is ectal in this group, and, 
together with its root-ganglion—G. Ehrenritteri, which lies upon the ectal 
surface of G. jugulare, but which does not seem to sustain anatomical re- 
lations with it—may be dissected from the ental trunk; XX. vagus and 
accessorius are most intimately related—their separation involving the 
rupture of interlacing fibre—and apparently constitute a single trunk; 
entad of this united trunk is X. liypoglossus. At the caudal border of this 
plexus X. accessorius is directed dorsad to be distributed to the muscles of 
the neck, and X. liypoglossus assumes ectal relations, crossing the ectal 
surface of X. vagus nearly at right angles, and takes its course ventrad, to 
the muscles of the tongue. As X. liypoglossus crosses X. vagus, it de- 
taches a filament to G. inferius (Fig. 5, 13). This region marks the origins 
of two other rami wTith whose terminal filaments X. vagus sustains inti- 
mate relations, XX. thyro-liyoideus and descendens noni. Fig-1- 
fir-2. 
%3. 
V- 
Hg.5. 1881.] 
127 
[Stowell 
15 mm. caudad of G. jugulare and dorsad of the origin of A. carotidea 
interna, X. vagus receives a second ganglionic enlargement, ganglion 
inferius, ganglion of the trunk (Fig. 5,1.). This ganglion has a fusi- 
form outline 5-8 mm. in caudo-ceplialic diameter and 2 mm. in dorso- 
ventral; it is of a pinkish color; is located ectad of (superficial to) and 
dorso-caudad of the closely-apposed superior cervical ganglion of X. sympa- 
thicus, to which it is very intimately related through anastomotic filaments; 
its cephalic extremity is apposed to the middle of the superior cervical 
ganglion. G. inferius does not embrace or involve the main trunk of X. 
accessorius; it is however joined at its dorso-ceplialic border by a large 
ramus given off from X. accessorius just peripherad of Px. gangliformis 
(Fig. 5, 14)-, it is the superficial origin of a large ramus of X. vagus, viz., 
X. laryngeus superior; it communicates with X. glosso-pharyngeus (IX) 
(Fig. 5, 17), X. accessorius (XI) (Fig. 5, 14), X. hypoglossus (XII) (Fig. 
5, 13), with the spinal nerves XX. vertebrales, in the loop which connects 
the first and second cervical nerves, and with X. sympathicus (entad of 
Px. gangliformis). 
In the cervical region X. vagus continues caudad from G. inferius asso- 
ciated with X. sympathicus in the sheath of A. carotidea primitiva. In 
the cephalic 20 mm. the trunk lies dorso-laterad of A. carotidea externa 
and A. carotidea primitiva, being concealed within the arterial sheath by 
the artery and by Y. jugularis interna. As the nerve approaches A. oc- 
cipitalis (?)* it lies laterad of A. carotidea primitiva and crosses the venter 
of A. occipitalis (?) at its origin; it resumes its dorso lateral relation 5-8 
mm. caudad of A. occipitalis (?) until it enters the thorax. The trunk of 
N. vagus in its cervical region caudad of G. inferius gives otf several ramuli 
which anastomose with ramuli of N. sympathicus to constitute a more or less 
dense plexus around the trachea and oesophagus; this is especially marked 
in the caudal portion of the cervical region. The distinctive courses of the 
sinistral and the dextral nerves in the thorax require separate descriptions. 
The principal rami of the cervical portion ofX. vagus are Rm 
auricularis, X. pharyngeus, and X. laryngeus superior. 
Km. auricularis, is a large anastomotic branch and has its superficial 
origin in the dorso-ental border of G. jugulare; its course is curved dorso- 
laterad and cephalad, and it enters the periotic bone, follows a groove along 
the dorso-caudal border of the tympanic bulla, traverses the petrous por- 
tion of the bone and enters aqueductus Fallopii at a point 2 mm. centrad 
of the origin of chorda tympani; a portion of Km. auricularis continues to 
the opening where it meets the dorsal branch of X. facialis, to be distributed 
to the ear. A considerable fasciculus crosses X. facialis and maybe traced 
to the cochlea (Fig. 5, 5). 2 mm. peripherad of its origin Rm. auricularis 
receives a considerable twig from X. glosso-pliaryngeus (IX), and about 
* This artery, 25 mm. caudad ot foramen of exit and dorsad, or 1-3 mm. dorso- 
cephalad of A. thyreoidea superior, seems to be allied to A. princeps cervicis. 
There are some objections to this homology, but the measurements given in the 
text identify it beyond question. Stowell.] 
[July 15, 
the same distance, still peripherad, an anastomotic filament front X. sympa- 
tliicus (Fig. 5, 6). 
N. pharyngeus, the pharyngeal branch, takes its superficial origin 
from the ventro-ental surface of X. vagus just caudad of the united trunks 
of XX. vagus and accessorius, 7 mm. caudad of G.jugulare and entad 
of the point where X. hypoglossus (XII) lies ectad of X. vagus ; its origin 
is, therefore, involved in Px. gangliformis. A considerable accession is 
traceable through the plexus to the accessory branch of X. accessorius. 
Its course is ventrad, parallel with X. glosso-pliaryngeus (IX), and only 
2-3 mm. caudad of that nerve ; it lies ectad of A. carotidea interna, and 
entad of V. jugularis interna and A. carotidea externa ; just peripherad of 
its origin it gives a twig caudad to the trunk, which may be traced to G. 
inferius (Fig. 5, 23). Opposite A. carotidea interna it divides into two 
rami (Fig. 5, 22, a, b), from which filaments are given to A. carotidea 
interna and to the adjacent Y. jugularis interna. From the cephalic 
ramus anastomotic filaments join N. glosso-pliaryngeus (IX) to form a 
plexus, from which filaments are distributed to the cephalic border of 
MM. pharyngis constrictor medius, and pharyngis constrictor superior ; 
others anastomose with filaments of N. sympathicus and form the pha- 
ryngeal plexus (Fig. 5), other filaments join X. hypoglossus (XII) in this 
plexus. The caudal ramus has its general course caudad ; 5 mm. peripherad 
of its origin, it subdivides into two ramuli, which may be designated, in 
view of their distribution, as the pharyngeal (Fig. 5-24), and the oesopha- 
geal (Fig. 5, 25) ; the pharyngeal ramulus is directed meso-dorsad and 
forms a loose network with the terminal filaments of the pharyngeal 
ramuli of X. glosso-pliaryngeus (IX)—Px. pharyngeus. The oesophageal 
ramulus gives filaments to MM. pharyngis constrictor medius and plia- 
ryngis constrictor inferior. 10-12 mm. caudad of the filaments to the mus- 
cles of the pharynx a considerable twig joins the cephalic ramus of X. 
laryngeus superior and receives an anastomotic filament from the caudal 
ramus of the same nerve. The oesophageal ramulus continues along the 
dorsum of the oesophagus caudad as far as the caudal third of the cervical 
portion, interlacing in the plexus around that viscus.* 
N. laryngeus superior, the superior laryngeal branch, is consider- 
ably larger than X. pharyngeus ; it takes its superficial origin from the 
ventral border of the middle region of G. inferius ; its course is imme- 
diately ventrad—occasionally it is directed caudad apposed to the main 
trunk and ectad of X. sympathicus, 8-10 mm., at which point it turns 
ventrad—and passes entad of A. carotidea primitiva, where it bifurcates 
into a cephalic, ental, ramus, N. laryngeus internus (Fig. 5, 7, 28) and 
a caudal, ectal, ramus, JY. laryngeus externus (Fig. 7. 29). 
N. laryngeus internus is much larger than X. laryngeus externus ; 
it accompanies A. laryngea superior, and with the artery perforates the 
hyo-thyroid membrane at the ventro-caudal border of the cephalic cornu 
* It sometimes occurs that the cancial ramus is detached caudad ot the cephalic 
ramus of N. pharyngeus : in this case it constitutes a second pharyngeal nerve ; 
this arrangement does not change its distribution. 129 
1881.] 
[Stowell 
of Ctl. thyroidea—A. laryngea superior is given off from A. carotidea 
externa, just caudad of the origin of A. carotidea interna ; its course is, 
therefore, at right angles with A. carotidea externa, 
N. laryngeus externus lies ectad of the larynx; it sends a pharyn- 
geal ramulus cephalad and entad of A. laryngea superior (Fig. 7, 30), 
which is distributed to M. constrictor pharyngis inferior, anastomoses with 
the oesophageal ramus of N. pharyngeus (Fig. 7, 31), gives terminal fila- 
ments to Px. pharyngeus and the pharyngeal mucous membrane; fila- 
ments of this ramulus anastomose with N. crico-thyroideus and unite in 
plexiform relation with N. sympathicus around A. thyroidea superior ; a 
twig of this pharyngeal ramulus detached just dorsad of the liyo-thyroid 
foramen, passes ventro-caudad to terminate in M. crico-thyroideus. This 
ramus sends a laryngeal ramulus ventro-caudad which lies entad of M. 
sterno-thyroideus, to which a few filaments are distributed, and is apposed 
to A. laryngea inferior, which artery it accompanies to the cricoid 
membrane as far as the ventrimeson (Fig. 7, 32) ; from this ramulus fila- 
ments are given to M. crico-thyroideus. A caudal ramulus is also de- 
tached whose course is dorsad of M. sterno-thyroideus and parallel with 
its dorsal border to Cp. tliyroideum (Fig. 7, 33) ; it gives filaments to M. 
crico-thyroideus and anastomotic filaments to N. descendens noni, which 
it joins opposite the origin of A. thyroidea superior. 
N. laryngeus internus enters the liyo-tliyroid foramen and divides into 
a cephalic and a caudal offset: the cephalic offset (Fig. 7, 34) accom- 
panies the ental portion of A. laryngea superior, pierces M. tliyro-arytse- 
noideus to which numerous filaments are distributed, takes its cephalic 
course obliquely toward the ventrimeson and perforates the thyro-hyoid 
membrane 2 mm. laterad of the meson. Terminal filaments of this offset 
supply the epiglottis (Fig. 7, 36), the aryheno-epiglottidean folds (Id. 37), 
the laryngeal glands (Id. 35), and the mucous membrane of the larynx 
(Id. 35, a). A twig given from the cephalic offset, 2 mm. periplierad of 
the foramen, passes entad of the apposed artery (A. laryngea superior 
entalis) and joins the caudal offset 2 mm. cephalad of the caudal border of 
Ctl. thyroidea (Fig. 7 and 8, 39). 
The caudal offset lies closely apposed to the ental surface of Ctl. 
thyroidea (Fig. 7 and 8, 38); its first twig is sent dorso-caudad and termi- 
nates upon M. crico-arytaenoideus lateralis, M. arytaenoideus and M. con- 
strictor pharyngis inferior (Fig. 8, 40); anastomotic filaments join in plex- 
iform relation with its dextral homologue and with the pharyngeal and 
oesophageal plexuses. The principal portion of the caudal offset at its union 
with the twig from the cephalic offset gives off radiating filaments upon 
the ectal surface of the arytamoid muscles which constitute a multiple 
palmate plexus (Fig. 8, 41.); a twig passes dorsad of the articular facet of 
Ctl. cricoidea and joins N. laryngeus inferior (Fig. 8. 42). Near the union 
of the twig and the offset, entad of cephalic border of Ctl. cricoidea several 
filaments penetrate M. crico-arytsenoideus and are distributed upon the 
mucous membrane of the larynx. /Pl.Phar. 
fig: 7 
Fig.^. 
Pg.ll 
(ifft 131 
1881.] 
[Stowell. 
Thoracic division of N. vagus sinister: The main trunk of X. 
vagus sinister enters the thorax dorsad of V. innorainata sinistra at tlie 
union of V. subclavia and V. jugularis externa, meso-dorsad of Y. verte- 
bralis and laterad of A. carotidea primitiva sinistra. In the thorax cephalad 
of the arch of A. aorta the nerve lies between AA. carotidea and subclavia 
meso-dorsad of A. sternalis until it reaches a point 10-15 nun. cephalad of 
A. aorta, at which point it rests upon the ventral surface of A. subclavia 
and crosses the arch ventro-laterad of the origin of A. subclavia. Opposite 
the origin of A. sternalis the nerve is crossed by X. phrenicus and lies 
dorso-laterad of this nerve in the area between the two arteries aforenamed. 
As X. vagus enters the thorax, two fasciculi from the middle and caudal 
areas respectively of the middle cervical ganglion of X. sympatlvicus, G. 
thyreoideum, connect X. vagus with X. sympathicus; these commissural 
fasciculi are about 3 mm. apart. Between a point opposite A. sternalis 
and the arch of A. aorta the trunk of X. vagus sustains intimate relations 
with X. sympathicus, X. cardiacus magnus and X. cardiacus minor 
through numerous anastomotic filaments which constitute aplexiform net- 
work around the arteries, trachea and oesophagus in this region of the 
thorax—AA. subclavise, carotidese primitives and innominata. Opposite 
the caudal border of the arch of A. aorta a considerable fasciculus from 
the main trunk about 5 mm. in length joins X. laryngeus inferior. 7 mm. 
peripherad of this fasciculus, where X. largyneus inferior bends around 
the arch of A. aorta, a ramulus is given oft' whose interlacings with rami 
from XX. vagus and sympathicus constitute a plexiform network which 
is related with the cardiac plexus. In its course caudad of arch of A. 
aorta. X. vagus passes dorsad of the root of the left lung. 
Pulmonary Kami: Between a point opposite the cephalic border of 
A. pulmonaris and 15 mm. caudad, X. vagus gives several ramuli meso- 
ventrad to anastomose with terminal filaments of X. cardiacus minor and 
X. laryngeus inferior in the formotion of the ectal (superficial) cardiac 
and the ventral (anterior) pulmonary plexuses. From the same region of 
the main trunk filaments are directed meso-dorsad, which interlace in a 
dense network with filaments of offsets detached from the main trunk of 
the area above named, and with terminal filaments of X. cardiacus minor, 
and other filaments from X. sympathicus to form on the ventral aspect of 
the trachea just cephalad of its bifurcation, a large plexus, the ental car- 
diac—Px. profundus magnus—from which filaments ramify upon the 
bronchi and have intimate relations with the plexiform network which is 
formed by filaments from the offsets named and accessory offsets from 
thoracic ganglia of X. sympathicus around the bronchi,—dorsal pulmonary 
plexus. Offsets from this plexus may be traced along the air tubes into 
the substance of the several lobes and upon the broncho-pulmonary mu- 
cous membrane of the sinistral lung. The ramuli which form the dorsal 
pulmonary plexus are noticeably larger than those given to the ventral 
plexus. 
(Esophageal Rami : Cephalad and caudad of the pulmonary rami 
PROC. AMER. PHILOS. SOC. XX. 111. Q. PRINTED MARCH 8, 1882. Stowell.] 
132 
[July 15, 
numerous filaments are directed dorsad, by whose anastomoses and union 
with N. sympathicus is formed the oesophageal plexus which embraces the 
entire length of the thoracic oesophagus. Caudad of the ramuli given to 
the pulmonary plexus, 15-20 mm. caudad of the caudal border of the 
arch of A. aorta, N. vagus sinister divides into sinistral or lateral and dex- 
tral or mesal rami (Fig. 9, 46) which lie respectively upon the sinistral 
dorsum and venter of the adjacent oesophagus. The lateral ramus trends 
dorso-caudad, and 50-60 mm. peripherad of its origin it unites with the 
lateral ramus of N. vagus dexter in a median line upon the dorsum of the 
(esophagus, to constitute a single dorsal trunk for about 25 mm. (Fig. 9, 
47) Numerous anastomotic filaments from the two rami of N. vagus 
sinister and the rami of N. vagus dexter interlace in the oesophageal plexus 
from which filaments are given to the muscular tissue and mucous mem- 
brane of the oesophagus. The united dorsal trunk perforates the dia- 
phragm and enters the abdomen as the gastric nerve. 
The mesal ramus of N. vagus sinister trends ventro-caudad, and 20-25 
mm. peripherad of its origin is joined by its dextral homologue (Fig. 9, 
48) and theke two mesal rami constitute a united ventral trunk which lies 
in the caudal mediastinum upon the venter of the oesophagus and perfo- 
rating the diaphragm near the meson, lies on the venter of the cardia (Fig. 
13). A slight twig connects the two mesal rami 2 mm. peripherad of 
their origins. From the thoracic portion of the ventral trunk anastomotic 
filaments are given to its homologue in the formation of the oesophageal 
plexus. 
The thoracic portion of N. vagus dexter lies ventrad of A. sub- 
clavia and mesad of A. sternalis; at the caudal border of A. subclavia it 
bends slightly dorsad to pass mesad of V. vertebralis at its junction with 
V. innominata, it continues laterad of the trachea, entad of V. azygos and 
dorsad of the root of the right lung. As the main trunk enters the thorax 
it sustains intimate relations through anastomotic twigs with N. cardiacus 
magnus, N. cardiacus minor and the inferior cervical ganglion of N. 
sympathicus (Fig. 10). 15 mm. caudad of A. subclavia. a considerable 
ramus is directed meso-caudad and accompanies a large ramus detached 
entad of V. azygos ; these cardiac rami pass meso-ventrad around the base 
of the right pulmonary artery and to the right auricle (Px. cardiacus ectalis). 
Three or four ramuli are given off between A. subclavia and Y. azygos 
whose ramifications interlace the plexus of the trachea and oesophagus. 
From the 12-14 mm. of the trunk dorsad of the lung, numerous filaments 
are directed mesad and ventrad to join the pulmonary plexus (Fig. 9). 
Caudad of this point and opposite the bifurcation of its sinistral homologue 
the dextral nerve bifurcates into lateral and.mesal rami (Fig. 9, 49); cau- 
dad of the bifurcation the lateral ramus trends dorso-caudad until it joins 
its sinistral homologue already described. The mesal ramus gives re- 
current ramuli cephalad to the dextral border of the pulmonary plexus. 
Several other anastomotic filaments are detached from the ramus between 
the root of the lung and the union with its fellow which terminate in the 
oesophageal plexus (Fig. 9). 1881.] 
133 
NX. laryngei inferiores, recurrent or inferior branches of N. 
vagus, tracheal recurrents, have the following general characters in com- 
mon, viz.: their general cephalic direction; their disposition along the 
dorso lateral border of the trachea; the anastomotic character of their 
ramuli; the distribution of the terminal filaments; the sensor}7 function of 
the fibre. Distinctive characters: their origin; their length; their disposi- 
tion in the thorax; the relative number of anastomotic filaments; the num- 
ber of tracheo-oesophageal ramuli. 
Special description : N. laryngeus inferior sinister, the sinistral re- 
current nerve, branches from the mesal aspect of the main trunk of N. 
vagus, 1-3 mm. cephalad of the arch of A. aorta (Fig. 9, 45); * its course 
is caudad, apposed to the mesal side of the main trunk as far as the root 
of A. subclavia sinistra where the main trunk crosses the arch of A. aorta. 
Upon the ventral aspect of the arch of A. aorta, N. laryngeus inferior sep- 
arates from the main trunk upon the mesal side, and twisting around the 
concave aspect of the arch about 1 mm. sinistrad of the obliterated 
“ductus arteriosus,” it trends meso-dorsad, and returns cephalad along 
the dorso-lateral border of the trachea, between the trachea and the oeso- 
phagus, as a “recurrent nerve’’ (Fig. 9, 50). At ihe caudal border of the 
larynx N. laryngeus detaches several ectal filaments to M. crico-thyroideus 
(Fig. 8), passes entad of a caudal twig of A. thyroidea superior, bends 
dorsad around the articular facet ofCtl. cricoidea (Fig. 8) and enters the 
larynx as an ental nerve. A slender anastomotic twig passes ectad of the 
arterial twig named and may be traced dorsad of the nerve trunk until it 
joins a corresponding twig from the caudal division of N. laryngeus su- 
perior (Fig. 7, ‘29, a). Pharyngeal ramuli from the ental nerve are dis- 
tributed to M. constrictor pliaryngis inferior; other dorsal filaments supply 
M. arytsenoideus posterior and M. arytamoideus; ventral filaments supply 
MM. crico arytsenoideus lateralis and thyro-arytsenoideus, while terminal 
filaments reach the sub-glottic mucous membrane. Upon the ectal surfaces 
of MM. crico-arytamoideus posterior and crico-arytamoideus lateralis a 
multiple palmate plexus is formed by anastomotic filaments of NN. 
laryngeus superior and laryngeus inferior (Fig. 8, J)l). 
N. laryngeus inferior dexter is detached from Ihe main trunk of 
N. vagus, 12 mm. cephalad of the origin of A. subclavia, where the main 
trunk is disposed upon the ventral aspect of A. subclavia (Fig. 10); N. 
laryngeus dexter is immediately directed caudad over the venter of the 
artery, is reflected around the caudal aspect, and assumes a meso-dorsal 
direction to the dextral side of the trachea, and is disposed like its sinistral 
liomologue, with the exception of having fewer anastomotic filaments. 
Peripherad of the origin of N. laryngeus inferior dexter, dorsad of A. sub- 
clavia, ramuli are given to the deep cardiac and the posterior pulmonary 
plexuses; another ramulus cephalad joins its sinistral fellow', a third, the 
thoracic cardiac, is directed caudad by the side of the main trunk of N. 
vagus dexter, and terminates in the dextral bronchial plexus. As N. 
* An occasional origin is 8-10 mm. cephalad of cephalic border ot arch of A. 
aorta. 
[Stowell Stowell.] 
[July 15, 
Fs.io. 
Fig.?. 
Fig-13 18S1.] 
135 
[Stowell 
laryngeus inferior dexter bends around A. subclavia, just dorsad of A. 
sternalis, a branch is given off caudad, which, 10-12 mm. from its origin, 
joins N. cardiacus minor (Fig. 10), and these apposed trunks are joined 5 
mm. peripherad by N. cardiacus magnus dexter, and .the trunk thus con- 
stituted passes dorsad of Y. cava descendens and A. innominata to the 
dorso-caudal border of the arch of A. aorta, where it terminates in Px. mag- 
nus profundus, from which filaments proceed to the ventral and dorsal 
coronary and the pulmonary plexuses. 
Tracheo-cesophageal ramuli of N. laryngeus inferior (Fig. 11, 12). 
General characters: these ramuli of the sinistral and dextral nerves 
have in common the following characters—their origin; general direction; 
numerous terminal filaments; the plexiform relation of these filaments; 
their mode of entering larynx; their distribution upon its mucous mem- 
brane; distribution of the dorsal filaments to oesophagus. Distinctive 
characters : the smaller number of ramuli from the dextral side than from 
the sinistral; the homologue of the first sinistral nerve is always found as 
a ramulus from the main trunk caudad of the origin of N. laryngeus in- 
ferior dexter (Fig. 12); the terminal filaments of the dextral side are less 
numerous than those of the corresponding nerves of the sinistral side.* 
Special description: opposite the cephalic border of the arch of A. aorta 
the first tracheal ramulus is detached (Fig. 11, l°rm.); a considerable offset 
is directed caudad from the origin to Px. magnus profundus; 2 mm. 
peripherad of origin an anastomotic filament joins N. vagus 8 mm. caudad 
of origin of IS. laryngeus inferior; 6 mm. peripherad of origin the ramulus 
bifurcates, the longer division is distributed upon the dorsum of the 
trachea 30 mm. cephalad of the arch of A. aorta; the shorter or caudal 
division sends filaments to Px. cardiacus ventralis, to Px. magnus profundus 
and to the bronchioli. 
Five mm. cephalad of the first ramulus a second is given to the venter and 
the sides of the trachea over that portion corresponding to the distribution 
of the cephalic division of the first ramus upon the dorsum. 
Ten mm. cephalad of the second ramulus and nearly opposite the origin 
of A. sternalis, the longest ramulus is detached ; this divides into three 
offsets, the caudal is distributed to the venter of the oesophagus, the 
median to the sides of the trachea, the cephalic lies just laterad of the 
ventrimeson and gives two considerable fasciculi, whose terminal filaments 
supply the walls of the trachea ; the terminal filaments of the ramulus 
are traceable nearly to Ctl. cricoidea. 
Opposite the sixth cervical vertebra the fourth ramulus is detached, 
whose filaments anastomose with the preceding ramulus, and supply the 
dorsum of the trachea and venter of adjacent oesophagus along the entire 
cervical region from the thorax to the larynx. 
The fifth tracheal ramulus takes its origin 10mm. caudad of Ctl. cricoidea 
* The double ramuli sometimes occur with separate origins; this apparent 
increase of ramuli may be regarded as a modification and not a violation of the 
plan. In the special description the details of measurements of a single speci- 
men are given. Stowell. 
136 
[July 15, 
(Fig. 8 and 11, 5°). This ramulus is largely if not exclusively oeso- 
phageal and joins in Px. pharyngeus; the caudal or recurrent portion is 
reflected caudad upon the oesophagus. 
Gastric nerves: Caudad of the diaphragm the dorsal gastric 
nerve splits into several terminal ramuli, the longest of which terminates 
in ganglion semi-lunare of the great solar plexus, Px. Solaris ; near the 
cardia numerous filaments are distributed to the cardia ; offsets supply the 
lesser curvature of the stomach, the plexus around A. coronaria ventriculi, 
and the dorsal surface of the stomach ; ramuli may be traced to the plexus 
around A. liepatica (Px. hepaticus), A. splenica (Px. splenicus), A. mesen- 
terica superior (Px. mesarseicUs). At the cardia, terminal filaments of the 
ventral trunk are distributed to the lesser curvature of the stomach, a 
few join terminal filaments of the dorsal trunk (Fig. 13), and others still 
maybe traced to the great solar plexus, from which ramuli enter the 
gastro-hepatic omentum and join the hepatic plexus. This anastomosis of 
the dorsal and ventral trunks in the solar plexus constitutes the “memor- 
able loop of Wrisberg.” 
SUMMARY. 
A. Anatomical. 1. Origin—12-14 filaments along a line ventro- 
laterad of Cp. restiforme, and by 4-6 filaments ventrad of oliva. 
2. Foramen of exit—foramen lacerum posterius. 
3. Ganglia—G. jugulare, in the proximal end of foramen of exit— 
G. inferius, 15mm. peripherad. 
4. Relations of ganglia—G. jugulare, with NN. facialis (VII), 
glosso-pharyngeus (IX), accessorius (XI), sympatliicus ; G. fnferius, with 
NX. glosso-pharyngeus (IX), accessorius (XI), hypoglossus (XII), 
pharyngeus, laryngeus superior, sympathicus. 
5. Px. gangliformis—the 5 mm. of trunk peripherad of G. jugu- 
lare ; it is formed by accessory portion of N. accessorius, anastomotic 
filaments between NN. vagus and accessoi'ius, filaments to N. pharyngeus, 
and N. sympathicus. 
6. Principal rami—respective origins and general distribution : Km. 
auricularis, G. jugulare to N. facialis; N. pharyngeus, Px. gangli- 
formis to Px. pharyngeus and oesopliagams ; N. laryngeus superior, G. 
inferius to larynx ; N. laryngeus inferior, N. vagus near arch of A. aorta 
to trachea and oesophagus ; Rm. cardiaci, trunk of N. vagus proximad 
of base of heart to Px. cardiaci; Rm. pulmonares, trunk of N. vagus 
proximad of root of lungs to Px. pulmonares ; anastomotic filaments to 
N. sympathicus. 
7. Bifurcation—dorso-laterad from roots of lungs into lateral and 
mesal rami. 
8. Formation of nerve trunks—dorsal trunk by union of lateral 
rami = dorsal gastric nerve (N. gastricus dorsalis)—ventral trunk by 
union of mesal rami = ventral gastric nerve (N. gastricus ventralis). 
9. Termination—ganglia semi-lunaria of Px. Solaris in loop of 
W risberg. 137 
18S1.] 
[Stowell. 
R. Physiological—sensibility of mucous membrane of pharynx, 
larynx, trachea, bronchi, bronchioli—motion of pharynx, larynx ; reflex 
movements of broncho pulmonary passages, oesophagus and stomach— 
action upon secretions, e. g., gastric juice, biliary products, etc.*—indirect 
influence upon phenomena of respiration and of “inhibition.” 
Explanation of the Xumbeks and Abbreviations used in thi 
Figures. 
A. bas., A. basilaris ; A. cb., A. cerebralis posterior; A. cbl., A. cere- 
bellosa inferior; A. ver., Arteria vertebralis ; Ar. el., area elliptiea (possibly 
related to olivary body) ; ?, elongated, pyriform area lateral from Ar. el., 
whose homology is not determined ; Cb., cerebrum ; Cbl., cerebellum ; 
Ch., chiasma; dpy., dorsipyramis (posterior pyramid) ; Ehr., G. Ehren- 
ritteri ; liph., hypophysis ; I., G. inferius ; J., G. jugulare ; mtc., meta- 
coelia (fourth ventricle) ; O., oliva, corpus olivarium (?) ; olf., lobus 
olfactorius ; opt., X. opticus ; Pe., G. petrosum ; Px.cli., plexuschoroideus 
lateralis ; Px. phar., plexus pharyngeus ; Pn., Pons Varolii; Iif., corpus 
restiforme; Ypy., ventripyramis (anterior pyramid) ; II., X. opticus; III., 
X. motor oculi ; Y., XX. trigemini ; VI., N. abducens ; YII., X. faci- 
alis ; VIII., X. auditorius, Portio mollis ; IX., X. glosso-pharyngeus ; 
X. X. vagus ; XI., X. accessorius 5 XII., X. hypoglossus : 1, accessory 
filament from X. glosso-pharyngeus ; 2, Rm. auricularis ; 3, anastomotic 
twig from J. to Pe. ; 4, filament from origin line of IX. to 2 ; 5, ramulus 
from 2 to cochlea ; 6, anastomotic twig to X. sympathicus ; 7, chorda 
tympani ; 8, anastomotic twig from Pe. to X. ; 10, Rm. accessorius from 
XI. ; 11, second accession from XI. ; 12, anastomotic filaments between 
X. and XI. ; 13, filament from XII. to I. ; 14, Rm. from XI. to I. ; 15, 
superior cervical ganglion of X. sympathicus ; 1(5, pharyngeal ramus from 
IX. at Pe. ; 17, anastomotic filament from 16 to I. ; 18, anastomotic fila- 
ment from 16 to Px. phar. ; 19, filament from 16 to X. laryngeus superior; 
20, cephalic ramus of IX. ; 21, caudal ramus of IX. ; 22, X. pharyngeus : 
22 a, cephalic ramus ; 22 b, caudal ramus ; 23, filament from 22 to I. ; 24, 
pharyngeal ramus of 22 b ; 25, oesophageal ramus of 22 b ; 26, filament 
from 25 to 22 a ; 27, X. laryngeus superior ; 28, cephalic = ental ramus; 
29, caudal = ectal ramus ; a, twig to 50 ; 30, pharyngeal ramus of 29 ; 
31, filament from 30 to 25 ; 32, Rm. of 29 to Mb. crico-thyroidea ; 33, to 
Cp. thyroideum, a, to descendens noni ; 34, cephalic offset of 28 ; 35, fila- 
ments to interior of larynx ; 36, to epiglottis ; 37, to arytamo-epiglottidean 
folds ; 38, caudal offset of 28 ; 39, twig from 34 to 38 ; 40, twig from 38 to 
M. arytamoideus, etc. ; 41, palmate plexus ; 42, ramus to 50 ; 43, X. car- 
diacus magnus sinister ; 44, X. cardiacus minor ; 45, origin of 50 ; 46, 
division of X. vagus sinister ; 47, union of lateral rami ; 48, union of 
mesal rami ; 49, division of X. vagus dexter ; 50, X. laryngeus inferior. 
*The extent to which secretions and excretions may be referred directly to N. 
vagus is questionable. 138 
Stowell.] 
Description of the figures. 
[July 15, 
Fig. l.—General view of venter of brain ; special reference to venter of 
medulla, area post pontilis, showing relations of lines of origin-filaments 
of NN. glosso-pharyngeus, vagus, and liypoglossus ; also ectal relations, 
ventripyramis (vpy.), area elliptica (ar. el.)> and the lateral tract (?). 
Pig. 2.—View of sinistral surface of brain, special reference to curved 
line of origin-filaments of X. vagus and to origin line (L) ventrad, and 
their relations ; the cephalic filaments of X. accessorius (XI) are in the 
depression line ventral from Ilf., while the caudal filaments have their 
origin in the depression line lateral from O. 
Pig. 3.—Diagram to show the origin of X. vagus ventro-lateral to Rf. ; 
also that X. accessorius (XI) has its cephalic filaments from the same de- 
pression line, and its caudal filaments from the depression line ventro- 
lateral to O ; X. liypoglossus (XII) is dorso-lateral to ar. el. 
Fig. 4.—Dorsal aspect of metencephalon (medulla) showing origins of 
XX. IX, X, XI ; metaccelia (mtc.), dorsipyramis (clpy.), corpus resti- 
forme (Rf.), oliva (0), and the lateral tract (?). 
Fig. 5.—To show relations of origin-filaments ; of Rm. auricularis ; of 
G. jugulare ; of G. petrosum ; of G. inferius. G. Ehrenritteri is removed 
from its normal relation which is ectal to G. jugulare, and is placed 
ceplialad to expose the parts. X. XII, is reflected dorsad to expose origin 
of X. pharyngeus and anastomotic ramus from Pe. The dotted lines 
represent XX. liyo-thyroideus and desce.ndens noni. Px. pliar. = 
pharyngeal plexus. 
Fig. 6. is Fig. 5, dissected to show Rm. accessorius given to J., and the 
second accession to the trunk peripheral to J. ; X. XII, is omitted as are 
the anastomotic filaments of Px. gangliformis ; the dotted line shows the 
direction of the filaments from X. XI, to X. pharyngeus. 
Fig. 7.—X. laryngeus superior ; origin; division ; distribution of ental 
or cephalic and ectal or caudal rami ; anastomotic relation between 
pharyngeal ramulus of the ectal ramus and the oesophageal ramus of X. 
pharyngeus. 
Dig. 8.—X. laryngeus inferior. To show the laryngeal relations of 
X. laryngeus inferior ; entad of Ctl. tliyroideus ; the palmate plexus ; the 
anastomotic filaments of XX. laryngeus superior and laryngeus inferior ; 
the pharyngeal ramus of X. laryngeus inferior (5°). 
Fig. 0.—X. laryngeus inferior sinister. To show its origin ; relations 
with A. aorta and adjacent plexus ; relations of X. vagus with X. 
sympatliicus ; division of X. vagus dorso-caudad of root of lungs ; the 
relations of the lateral and the mesal rami ; the dorsal and the ventral 
pulmonary plexus ; the formation and the relations of the dorsal and the 
ventral nerve trunks. 
Fig. 10.—X. laryngeus inferior dexter. To show its origin ; its relations 
with A. subclavia ; relations of X. vagus with X. sympatliicus. 
Fig. 11 and 12.—Tracheo-oesophageal ramuli of X. laryngeus inferior 
sinister and dexter respectively. 
Fig 13.—Distribution and relations of the ventral gastric nerve and the 
ramus which terminates in the dextral G. semilunare of Px. Solaris.