882 
of the lungs and stomach, and hence its appel- 
lation of pneumo-gastric. 
The nervus vagus arises by several filaments, 
generally from six to ten, from the restiform body 
of the medulla oblongata, parallel to and a little 
posterivr to the groove between the olivary and 
restiform bodies, and from a line to a line and a 
half distant from the posterior edge of the olivary 
body. Thearciform band of superficial filaments 
passing between the anterior eases and res- 
tiform bodies cross among the lower filaments 
of this nerve. The filaments of the vagus are 
attached to the restiform body in a vertical, 
straight, and thin band of from three to four 
lines in length, the upper end of which is eh on 
rated from the lower edge of the glosso-pha- 
eal nerve by a few small bloodvessels only. 
he upper half of these filaments of the vagus 
are at their origin closely approximated, so that 
the lower edge of the one above is in contact 
with the upper edge of the one below, while 
the lower filaments, pray the two last, are 
considerably more distant from each other. 
The lowest filament is placed only a little 
above and in the same line with the uppermost 
filament of the spinal accessory, and it is fre- 
quently difficult to determine where the fila- 
ments of the accessory begin, and where those 
of the vagus end. From this origin each vagus 
roceeds forwards and outwards between the 
ower surface of the lateral lobe of the cerebel- 
lum and that portion of the dura mater cover- 
ing the basilar process of the occipital bone, to 
reach the foramen lacerum posterius, through 
the anterior part of which opening it escapes 
from the interior of the cranium. In this part 
of its course it frequently anastomoses with 
the glosso-pharyngeal, and its filaments be- 
come more subdivided, but at the same time 
more closely aggregated, so that it is thicker 
and narrower. On reaching the foramen lace- 
rum posterius it enters a sheath or canal in the 
dura mater, anterior and a little internal to the 
commencement of the internal jugular vein, 
immediately anterior to the spinal accessory 
nerve, and posterior to the glosso-pharyngeal. 
As these three nerves enter the foramen lace- 
rum, they perforate the dura mater, the glosso- 
pharyngeal by a separate and distinct opening, 
the nervus vagus and spinal accessory by an 
opening common to both. Sometimes there is 
a small bridle of dura mater, at other times 
only a fold of the arachnoid separating the 
vagus and accessory at this part. At the lower 
part of the foramen lacerum the spinal acces- 
sory is closely applied to the posterior surface 
of the vagus. e dura mater is prolonged 
downwards into the foramen lacerum upon 
these three nerves in the form of two sheaths, 
one sheath surrounding the glosso-pharyngeal, 
and the other the vagus and accessory. From 
the proximity of these three nerves, as they 
pass through the foramen lacerum posterius, 
and from their intimate connection in some 
parts of their course and subsequent distribu- 
tion, they were long considered to form only a 
single nerve. 
As the’ vagus lies in the foramen lacerum 
it presents a greyish oblong swelling, resem- 
PAR VAGUM. 
bling the ganglion . the ior root of 
a spinal nerve ( ion prunum nervi vagi 
of Waser, pis one radicis n. v. of , 
anglion superius n. v., ganglion jugulare n. v. 
is ganglionic enlargement begins im 
ately after the nerve has entered the foramen 
lacerum, so that its upper edge may be some- 
times seen from within: the cranium ; it is of an é 
oval form, and it extends the course of 
the nerve from a line. and a half to two lines.* 
Mr. James Spencet has pointed out that a 
small filament bayer ae the lower Bon: of 
the vagus passes over the posterior surface of 
this ganglion without entering it, and joins” 
itself to the superior filaments of the spinal 
accessory.[ This fact, as we shall afterwards 
find, has a direct bearing upon the physi 
of the nerve. - A communicating filament 
between the ganglion superius of the vagus and 
the superior cervical ganglion of the sympathe- 
tic, another between it and the ganglion petro- 
sum of the glosso-pharyngeal, (vide article 
Grosso-PuaryNGEAL,) and one or St be- 
tween it and the spinal accessory. From the 
* Arnold (Der Kopftheil des vegetativen ere 
vensystems beim Menschen. S. 107) describes 
ganglion as varying little in size, and as 
a line and a half to aline and three quarters in 
breadth, a line to a line and a half in a a and 
three quarters to one line in thickness. He found 
a difference of about two lines between the mea- 
surement of the circumference of the . gneleeey 
the trunk of the nerve immediately w, the for- — 
mer generally measuring five and the latter three — 
lines. Bischoff (Nervi Accessorii Willisii, Anato- 
mia et Physiologia, 1832, p. 20) gives ne 
measurements as those of Arnold, from whom he has 
evidently copied them. Bendz (De Connexu inter 
Nervum Vagum et Accessorium Willisii, 1836, 
p- 17) describes it as a rounded saa ec 
flattened, measuring about two lines in the 
posterior diameter, and nearly two lines in the 
vertical direction. Valentin (Séemmerring’s Vom 
Baue des Menschlichen Korpers, Hirn und Ner- 
venlehre. Vierter Band. 1841. S. 482) deseril 
as an oblong rounded swelling, somewhat 
and about from a line and three quarters to two au 
a half lines in length, » bee Surgical el 
¢ Edinburgh Medical an i ourna 
No, 153, 1842. i 
¢ Remak (Froriep’s neue Notizen for 189; 
No. 54) states that some of the filaments of t 
vagus do not pass throagh this superior ¢ 
the vagus in the dog, cat, and rabbit; and Vol 
mann (Miiller’s Archives, Heft v. 1840) confir 
this observation of Remak on the dog; and furth 
mentions that the same enlargement exists i 
sheep, while in the calf all the Pp 
through the ganglion. The in of such | 
sections, especially those made on the human) 
cies, and the physiological inferences deduc ; 
them, have been called in question, (e.g. He 
Miiller’s Archives for 1844, p.336, and Bischo 
the same work for 1833, p. 156), om the gre 
that this anatomical ement is not- con 
and besides that it is difficult to distingnish betw 
the lower fibres of the root of the vagus ant 
upper fibres of the root of the nervus accessor 
i Bendz describes and delineates (De 
inter Neryum Vagum et Accessorium 
Hanniz, 1836) two small communicati 
passing between the spinal accessory the ga 
glion jugulare of the vagus. Valentin (Séemme 
ring Vom Baue des Menschlichen Korpers, H 
und Nervenlehre, Vierter Band, 1841) deseribe: 
similar anastomosis. Arnold (Icones v 
, 
‘y 
, 
t 
are 
a 
