llary plexus traverse the axillary
space; such nerves, for example, as those named intercosto-humeral, seen
lying on the latissimus tendon, O, Plate 11. The vein named cephalic, S,
enters the axillary space at that cellular interval occurring between
the clavicular origin of the deltoid muscle, G, and the humeral
attachment of the pectoralis major, H, which interval marks the place of
incision for tying the axillary artery.

The general course of the main vessels through the axillary space would
be indicated with sufficient accuracy by a line drawn from the middle of
the clavicle, R R, Plate 11, to the inner border of the biceps muscle,
N. In this direction of the axillary vessels, the coracoid process, L*,
from which arises the tendon of the pectoralis minor muscle, L, is to be
taken as a sure guide to the place of the artery, b, which passes, in
general, close to the inner side of this bony process. Even in the
undissected body the coracoid process may be felt as a fixed resisting
point at that cellular interval between the clavicular attachments of
the deltoid and great pectoral muscles. Whatever necessity shall require
a ligature to be placed around the axillary in preference to the
subclavian artery, must, of course, be determined by the particular
case; but certain it is that the main artery, at the place B, a little
above the clavicle, will always be found freer and more isolated from
its accompanying nerves and vein, and also more easily reached, owing to
its comparatively superficial situation, than when this vessel has
become axillary. The incision required to be made, in order to reach the
axillary artery, b, from the forepart, through the skin, both pectoral
muscles, and different layers of fasciae, must be very deep, especially
in muscular, well-conditioned bodies; and even when the level of the
vessel is gained, it will be found much complicated by its own branches,
some of which overlie it, as also by the plexus of nerves, D, Plate 12,
which embraces it on all sides, while the large axillary vein, a, Plate
11, nearly conceals it in front. This vein in Plate 11 is drawn somewhat
apart from the artery.

Sometimes the axillary artery is double, in consequence of its high
division into brachial branches. But as this peculiarity of premature
division never takes place so high up as where the vessel, B, Plate 11,
overarches the first rib, F, this circumstance should also have some
weight with the operator.