ide, and is most commonly
attended by the internal cutaneous nerve, seen lying upon it in Plate
11, as also by that other cutaneous branch of the brachial plexus, named
the nerve of Wrisberg. If a longitudinal incision in the course of the
brachial artery be made (avoiding the basilic vein) through the
integument down to the fascia of the arm, and the latter structure be
slit open on the director, the artery will be exposed, having the median
nerve lying on its outer side in the upper third of the arm, and passing
to its inner side towards the bend of the elbow, as at b*, Plate 12. The
superior and inferior profunda arteries, seen springing above and below
the point b, Plate 12, are those vessels of most importance which are
given off from the brachial artery, but the situation of their origin is
very various. The ulnar nerve, f, lies close to the inner side of the
main arterial trunk, as this latter leaves the axilla, but from this
place to the inner condyle, Q, behind which the ulnar nerve passes into
the forearm, the nerve and artery become gradually more and more
separated from each other in their descent. The musculo-spiral nerve, g,
winds under the brachial artery at the middle of the arm, but as this
nerve passes deep between the short and long heads of the triceps
muscle, P, and behind the humerus to gain the outer aspect of the limb,
a little care will suffice for avoiding the inclusion of it in the
ligature.

The brachial artery may be so effectually compressed by the fingers on
the tourniquet, against the humerus in any part of its course through
the arm, as to stop pulsation at the wrist.

The tourniquet is a less manageable and not more certain compressor of
the arterial trunk than is the hand of an intelligent assistant. At
every region of the course of an artery where the tourniquet is
applicable, a sufficient compression by the hand is also attainable with
greater ease to the patient; and the hand may compress the vessel at
certain regions where the tourniquet would be of little or no use, or
attended with inconvenience, as in the locality of the subclavian
artery, passing over the first rib, or the femoral artery, passing over
the pubic bone, or the carotid vessels in the neighbourhood of the
trachea, as they lie on the fore part of the cervical spinal column.

DESCRIPTION OF PLATES 11 & 12.

PLATE 11.

A. Subclavian vein, crossed by a branch of the brachial plexus given to
the subclavius mus