e 10, still,
that these vessels themselves, in consequence of their separate
condition, will materially influence the like operation in respect to
them. An aneurism occurring in the first part of the course of the right
subclavian artery, at the locality a, Plate 9, will lie so close to the
origin of the right common carotid as to require a ligature to be passed
around the innominate common trunk, thus cutting off the flow of blood
from both vessels; whereas an aneurism implicating either the left
common carotid at the point A, or the left subclavian artery at the
point B, does not, of course, require that both vessels should be
included in the same ligature. There seems to be, therefore, a greater
probability of effectually treating an aneurism of the left
brachio-cephalic vessels by ligature than attaches to those of the right
side; for if space between collateral branches, and also a lesser
caliber of arterial trunk, be advantages, allowing the ligature to hold
more firmly, then the vessels of the left side of the root of the neck
manifest these advantages more frequently than those of the right, which
spring from a common trunk. Whenever, therefore, the "peculiarity" of a
separate aortic origin of the right carotid and subclavian arteries
occurs, it is to be regarded more as a happy advantage than otherwise.

DESCRIPTION OF PLATES 9 & 10.

PLATE 9.

A. Innominate artery, at its point of bifurcation.

B. Right internal jugular vein, joining the subclavian vein.

C. Sternal end of the right clavicle.

D. Trachea.

E. Right sterno-thyroid muscle, cut.

F. Right sterno-hyoid muscle, cut.

G. Right sterno-mastoid muscle, cut.

a. Right vagus nerve, crossing the subclavian artery.

b. Anterior jugular vein, piercing the cervical fascia to join the
subclavian vein.

[Illustration: Neck and upper chest, showing blood vessels, muscles and
other internal organs.]
Plate 9

PLATE 10.

A. Common carotid artery of left side.

B. Left subclavian artery, having b, the vagus nerve, between it and A.

C. Lower end of left internal jugular vein, joining--

D. Left subclavian vein, which lies anterior to d, the scalenus anticus
muscle.

E. Anterior jugular vein, coursing beneath sterno-mastoid muscle and
over the fascia.

F. Deep cervical fascia, enclosing in its layers f f f, the several
muscles.

G. Left sterno-mastoid muscle, cut across, and separated from g g, its
sternal and clavic