An incision should be made through the integuments along the internal margin of the sterno-mastoid muscle, for the extent of about three inches above the clavicle. In most cases a vein may be observed descending along the anterior margin of the sterno-mastoid muscle communicating with the facial vein above, and with the thyroid plexus of veins, or the subclavian vein, below: care must be taken not to injure this. A portion of the fascia at the lower part of the incision should next be raised in the forceps, and divided in a horizontal direction: through the opening thus made a director should bo introduced from below upwards in the line of the first incision, and the fascia slit up on it as far as may be necessary. The lips of the wound are now to be separated by retractors, the sterno-mastoid muscle being drawn outwards, and the sterno-hyoid and sterno-thyroid inwards. The sheath of the vessels will be thus exposed, and on the front of it may be seen the internal branch of the descendens noni nerve, which should be drawn inwards, and the sheath divided in the same cautious way as the fascia.

* Dublin Pathological Reports, 1842, p. 197.

A ligature is now to be passed round the artery, directing the needle from without inwards, in order to avoid the jugular vein, which sometimes suddenly swells out during expiration, and then contracts during inspiration. As the vein fills at both its upper and lower extremity, an assistant should in such case compress it both at the upper and lower angle of the wound. In very many cases the vein, so far from giving any trouble, is not even observed during the whole of the operations. In a case operated on by Dr. Browne, of the Navan County Infirmary, "the internal jugular vein did not appear, nor was it a source of the slightest inconvenience during the operations." In a similar case related by Mr. Hodgson, " the jugular vein afforded no trouble in the operation ; it was not even seen." Mr. Bead, of Dublin, whose experience is very considerable, is reported by Mr. Hargrave to have said that " in all the operations he performed, or assisted in, on this vessel, the vein was not found to interfere with the operation, nor was it even seen."* The existence of the fibrous septum extending from the anterior to the posterior part of the sheath, and thus separating the artery from the vein, may explain this fact. Care is to be taken to avoid including the pneumogastric nerve, which lies behind and between the vessels: the nerve should be drawn outwards with the vein. The sympathetic and recurrent nerves are behind the sheath, and there is comparatively little danger of including them in the ligature. In operating on the left side, the proximity of the thoracic duct is to be borne in mind.