In some instances, particularly in short-necked persons, the omo-hyoideus lies close to the clavicle, and requires to be drawn upward and outward from it. In others, the lowest nerve of the axillary plexus lies over the artery, and may be mistaken for it. When the veins coming from the neck are large and numerous, great care should be taken to avoid injuring them, as they frequently cause not only much hemorrhage, but great delay. Great care must also be taken in all these operations to prevent the ingress of air into any of the veins which may by accident be opened, as its admission in quantity has occasioned sudden death, although the entrance of a few bubbles may not be so dangerous as has been supposed.
236. When the axillary artery is to be tied for a _wound_ caused by a sharp-pointed or other instrument which has been forced through the pectoral muscle or under it from the axilla, the patient is to be firmly supported or placed in the horizontal position, the arm to be slightly separated from the body, and an incision made in the course of the axillary artery, through the integuments, superficial fascia, and the great pectoral muscle--in fact, through the anterior fold of the armpit. The length of the incision will depend on the part at which the artery is to be secured. The parts divided being separated, the pectoralis minor will be seen crossing to the coracoid process at the upper part of the wound, and the artery may be felt below it, inclosed in its cellular sheath, with the nerves of the arm and its venæ comites. All other modes of attempting this operation are unworthy consideration, and ought to be discarded as dangerous and insufficient.
At the lower edge of the pectoralis minor, the artery is crossed by the outer of the venæ comites, which passes between the external cutaneous and the external origin of the median nerve, at the spot where they separate from the plexus. The artery may be tied below this separation, or the nerves and vein may be drawn to the outside, and the artery tied above the union of the external with the internal root of the median nerve as high as the origin of the arteria thoracica acromialis, the pectoralis minor being either raised and pushed upward, or divided if necessary. The internal root of the median nerve is in connection with the internal cutaneous and ulnar nerves; the larger of the venæ comites is to the inside and behind, but as it ascends it receives its fellow, and with the cephalic vein forms in front of the artery the subclavian vein.