hich are frequently the subject of
operation. The anatomy of this region becomes, therefore, important;
forasmuch as the operation which is intended to concern the veins alone,
may also, by accident, include the main arterial vessel which they
overlie. The nerves, which are seen to accompany the veins
superficially, as well as that which accompanies the more
deeply-situated artery, are, for the same reason, required to be known.

The course of the brachial artery along the inner border of the biceps
muscle is comparatively superficial, from the point where it leaves the
axilla to the bend of the elbow. In the whole of this course it is
covered by the fascia of the arm, which serves to isolate it from the
superficial basilic vein, B, and the internal cutaneous nerve, both of
which nevertheless overlie the artery. The median nerve, d, Plate 15,
accompanies the artery in its proper sheath, which is a duplication of
the common fascia; and in this sheath are also situated the venae
comites, making frequent loops around the artery. The median nerve
itself, D, Plate 16, takes a direct course down the arm; and the
different relative positions which this nerve holds in reference to the
artery, C, at the upper end, the middle, and the lower end of the arm,
occur mainly in consequence of the undulating character of the vessel
itself.

When it is required to ligature the artery in the middle of the arm, the
median nerve will be found, in general, at its outer side, between it
and the biceps; but as the course of the artery is from the inner side
of the biceps to the middle of the bend of the elbow, so we find it
passing under the nerve to gain this locality, C, Plate 16, where the
median nerve, D, then becomes situated at the inner side of the vessel.
The median nerve, thus found to be differently situated in reference to
the brachial artery, at the upper, the middle, and the lower part of the
arm, is (with these facts always held in memory) taken as the guide to
that vessel. An incision made of sufficient length (an inch and a half,
more or less) over the course of the artery, and to the outer side of
the basilic vein, B, Plate 16, will divide the skin, subcutaneous
adipose membrane, which varies much in thickness in several individuals,
and will next expose the common fascial envelope of the arm. When this
fascia is opened, by dividing it on the director, the artery becomes
exposed; the median nerve is then to be separated from