t the opening
may be made with most advantage according to the longitudinal axis of
the vessel; for the vessel while being cut open in this direction, is
less likely to swerve from the point of the lancet than if it were to be
incised across, which latter mode is also far more liable to implicate
the artery. Besides, as the nerves course along the veins from above
downwards--making, with each other, and with the vessels, but very acute
angles--all incisions made longitudinally in these vessels, will not be
so likely to divide any of these nerves as when the instrument is
directed to cut crossways.

The brachial artery usually divides, at the bend of the elbow, into the
radial, the ulnar, and the interosseous branches. The point F, Plate 16,
is the common place of division, and this will be seen in the Plate to
be somewhat below the level of the inner condyle, e. From that place,
where the radial and ulnar arteries spring, these vessels traverse the
forearm, in general under cover of the muscles and fascia, but
occasionally superficial to both these structures. The radial artery, F
N, Plate 16, takes a comparatively superficial course along the radial
border of the forearm, and is accompanied, for the upper two-thirds of
its length, by the radial branch of the musculo-spiral nerve, seen in
Plate 16, at the outer side of the vessel. The supinator radii longus
muscle in general overlaps, with its inner border, both the radial
artery and nerve. At the situation of the radial pulse, I, Plate 15, the
artery is not accompanied by the nerve, for this latter will be seen, in
plate 16, to pass outward, under the tendon of the supinator muscle, to
the integuments.

The ulnar artery, whose origin is seen near F, Plate 16, passes deeply
beneath the superficial flexor muscles, L M K, and the pronator teres,
I, and first emerges from under cover of these at the point O, from
which point to S, Plate 16, the artery may be felt, in the living body,
obscurely beating as the ulnar pulse. On the inner border of the ulnar
artery, and in close connexion with it, the ulnar nerve may be seen
looped round by small branches of the vessel.

The radial and ulnar arteries may be exposed and ligatured in any part
of their course; but of the two, the radial vessel can be reached with
greater facility, owing to its comparatively superficial situation. The
inner border of the supinator muscle, G, Plate 16, is the guide to the
radial artery; and the o