\ 
: 
NERVOUS SYSTEM. 
_ pular branch, abundantly restore the circula- 
tion. Should the carotid have been tied, its 
mesial communications, already mentioned, es- 
pecially those within the skull, and about the 
thyroid gland,—assisted at those places and 
elsewhere by anastomoses with the subclavian, 
—adequately fulfil their vicarious duty. So 
abundant are these various communications, 
that the ligature of a main trunk, in the dead 
subject, in no degree interferes with the dis- 
tension of its branches by fine injection: if we 
inject water, or any equally fluid material, 
through one carotid artery, it freely returns by 
the other. Under these circumstances, it ex- 
cites our surprise that the cure of aneurism by 
Tigature should be so certain; for the amount 
circulation through the affected vessel can at 
first be little affected, and the arrest and ulti- 
mate cure of the disease must be referred rather 
to the withdrawal of a distensive impulse than 
to any considerable derivation of current. It 
Seems to have been considered, in operating 
for aneurism, that, so long as no large branch 
arose from the vessel closely on the cardiac 
side of the ligature, it mattered not what 
branches might arise on its distal side,—how 
large, or how near. In many instances secon- 
dary hemorrhage, inducing death, has mani- 
festly depended on defective adhesion at the 
_ distal side of the ligature, and for an ob- 
vious reason. ‘The condition of that part of the 
artery has been neglected : it has been thought 
_ unimportant though a large vessel should arise 
just beyond the ligature ; or, if a great length 
of artery have been injudiciously denuded, the 
cardiac portion has had an exclusive preference 
of security given to it, by the ligature being 
drawn as high as possible in that direction. 
If an equal attention were bestowed on both 
sides of the proposed seat of ligature,—if like 
Care were taken, in both directions, to avoid 
the likelihood of disturbance to the adhesive 
eee by side currents,—if, where the artery 
has been much denuded, (instead of a single 
thread being applied at the cardiac extremity 
of that isolated portion, by which plan the 
Succeeding part of the tube,—though sepa- 
rated from its connexions, and likely to ulce- 
Tate or slough,—is yet left open to the stream 
of recurrent blood,) a second ligature were 
placed at the distal limit of the endangered 
part, there would seem no greater reason to 
anticipate the occurrence of secondary hemor- 
rhage than when arteries are tied after an am- 
putation. 
_ 3. Anomalous arrangement of the cervical 
vessels is a contingency which the surgeon 
must bear in mind. Most of these are com- 
prehended in the abnormalities of the arch 
already described. (See Aorta.) The ex- 
istence of a median inferior thyroid artery, de- 
rived from the arch, or from the arteria inno- 
minata;—the irregular passage of the right 
subclavian artery from the left side, behind the 
esophagus, or between that tube and the tra- 
chea ;—an early division of the carotid, even 
to nearly the level of the sternum, or so late a 
one, that the common trunk furnishes many, 
or most, of the branches normally originating 
585 
from the external ;—the absence of .an arteria 
innominata, its branches arising S.parately 
from the arch, or in irregular combination with 
those of the left side; the occasional origin of 
the vertebral from the common carotid,* are 
the deviations which it most behoves the prac- 
titioner to remember. 
4. Certain veins in the neck have an anato- 
mical disposition, rendering them liable, when 
opened in surgical operations, to become chan- 
nels for inspiration of air to the cavities of the 
heart, the fatal tendency of which is well 
known. The internal jugular, innominate, and 
subclavian veins are, as M. Bérard notices, 
“at the root of the neck, so firmly united by 
fascial lamin and cords to the adjacent bones 
and muscles, that they do not collapse on divi- 
sion, but gape:” and it is obvious that this cir- 
cumstance (but for which they would be flat- 
tened, and rendered impervious, by the atmo- 
spheric pressure on their outward surface) must 
expose them remarkably (perhaps alone) toa 
dangerous participation in the inhaustive move- 
ments of breathing. M. Velpeau (who has 
written a paper of excellent critical research on 
the subjectt) recommends the following pre- 
cautions in approaching veins of the nature 
described (veines canalisées): studiously to 
avoid wounding them,—to detach no deeply 
fixed tumour from its adhesions, without 
having previously commanded the vessels at 
its base,—and to maintain no unnecessary ten- 
sion on the fascie, by forced positions of the 
shoulder. 
For the BIBLIOGRAPHY see that of ANATOMY 
(INrRODUCTION), and the references under the 
various articles referred to. One work may be 
Porarein at as belonging to the region, and as 
aving, more than any book of the age, given an 
impetus to the study of anatomy in that most prac- 
tical form, which interests the surgeon by unfolding 
the relations of disease and of operative measures, 
Through the happy combination referred to, the 
mere barren description of regions has become 
surgical anatomy ; and to Dr. Colles of Dublin, and 
Allan Burns of Glasgow, belongs the merit of 
having, first in this country, illustrated that natural 
connexion, which gives to anatomy the interest of 
application, and to practice the security of know- 
ledge. 
(John Simon.) 
NERVOUS SYSTEM.—In proportion as 
our knowledge of the intimate texture of ani- 
mal and vegetable organisms advances, the 
doctrine gains ground that many of the phe- 
nomena, called vital, are to be attributed to 
the special endowments of distinct forms of 
animal or vegetable matter ; distinct as regards 
their anatomical characters as well as their 
chemical composition ; distinct, therefore, as 
* A single instance has occurred to me in the 
dissecting-room, of an arrangement, which I believe 
to be very rare. An innominata (for so its origin 
and course entitled it to be named) divided at the 
sterno-clavicular joint into common carotid and 
vertebral: the right subclavian arose from the de- 
scending part of the arch, and directed itself to the 
scalene space by passing behind the cesophagus. 
+ Médecine Opératoire; and Lettre sur V’Intro- 
duction de l’Air dans les Veines. Paris, 1838, 
