The external carotid, and also most of its principal branches, have been tied for aneurisms, wounds, goitres, enlargement of the tongue, vascular tumours on occiput and other lesions; also as a first stage in the operation of extirpation of the upper jaw, for the purpose of preventing hæmorrhage. However, such operations are rare, and will probably become rarer still, and it is hardly necessary to describe the operations on each seriatim.
Aneurism of the external carotid or branches are rare; if idiopathic, ligature of the common carotid will be found at once easier, not more dangerous, and more effectual than ligature of the branch; if traumatic, the aneurism itself should be attacked, and the bleeding point secured by a double ligature. Wounds are common enough, but if accessible at all, the injured vessel should be tied at the bleeding point; if inaccessible (and under this head we may include wounds of the internal carotid), the common carotid must be tied.
No one would think of trying the superior thyroids for goitre, unless they were so manifestly enlarged, tortuous, and pulsating, as to render the operation so simple (from their superficial position) as to require no special directions; besides this, the cases in which it has been already done have given very little encouragement to repeat it.
As cases may occur in which any diminution of the cerebral supply is contra-indicated, and thus the more difficult ligature of the external carotid may be preferred to the more simple operation on the common trunk, and as the lingual may require ligature near its root, in consequence of obstinate hæmorrhage from the tongue, short directions are given for the performance of both these operations.
1. Ligature of External Carotid.—Head in same position as for the common carotid. A straight incision parallel with the anterior edge of sterno-mastoid, but about half an inch in front of it, must begin almost at angle of jaw, and extend downwards nearly to the level of the thyroid cartilage. Cautiously divide skin, platysma, and fascia; the lower end of the parotid must be pulled upwards, and the veins, which are numerous, cautiously separated. The anterior border of the sterno-mastoid must be pulled backwards, and the digastric and stylo-hyoid forwards and inwards. The superior laryngeal nerve which lies behind the vessel must be avoided.
2. Ligature of Lingual.—To secure this vessel either before it becomes concealed by the hyo-glossus, or after it is under the muscle, a curved incision is necessary, following the line of the hyoid bone, and especially of its greater cornu, but a line or two above its upper border. After the skin and platysma are divided, the posterior belly of the digastric must be recognised, which again will guide to the posterior edge of the hyo-glossus. The edge of the sub-maxillary gland may very probably require to be raised out of the way. The artery can then be secured, either before it dips under the hyo-glossus muscle, or after it has done so, by the division of a few of its fibres on a director. Care is needed to avoid injury of the hypo-glossal nerve, which lies above the muscle.
The internal carotid artery occasionally, but very rarely, is the subject of aneurism. It may, like any other artery, be wounded, especially from the fauces. The treatment of either of these lesions is ligature of the common carotid itself, in preference to ligature of the internal carotid. Guthrie's operation for securing the bleeding internal carotid at the injured spot, by dividing and turning up the ramus of the lower jaw, has never been performed in the living body, and is so difficult, dangerous, and unnecessary, as not to merit description.
Ligature of Subclavian.—Note.—In consequence of the difference in the origin, and variety in the anatomical relations of the right and left subclavian arteries, in so far at least as their first stage is concerned, it is necessary to give a very brief separate account of each.
Right Subclavian.—The innominate artery divides into the right subclavian and right carotid exactly behind the sterno-clavicular articulation. The right subclavian extends from this point in an arched form across the neck, between the scalene muscles, over the apex of the pleura, till, passing under cover of the clavicle, it changes its name to axillary at the lower end of the first rib. For convenience of description, the artery is divided into three parts, which have very various anatomical relations, and differ from each other much in their amenability to surgical treatment by ligature. The anterior scalenus muscle defines the three parts, the first extending to the inner border of the muscle, the second being concealed by the muscle, and the third reaching from its outer border to the lower border of the first rib.
Branches of the Subclavian.—While the deep relations of pleura, veins, and nerves can be noticed under the head of each operation in detail, one anatomical point must never be forgotten as influencing very much the success of all surgical interference with the subclavian arteries—i.e. the branches given off. To give any chance of success in the application of a ligature to such a large vessel, so near the heart, a large portion of artery free from branches is required, that the clot may be long, firm, and undisturbed. The first part of the subclavian gives off the vertebral, thyroid axis, and internal mammary; the second, the superior intercostal; while the third part has in most cases no branch whatever. In these anatomical differences we find the reason for the almost invariable fatality resulting on any interference with the first and second parts, and the comparative safety of ligature of the third part, without requiring to account for the difference on other grounds, such as depth of part, importance of nervous relations, or nearer proximity to the heart.